Note: This page contains sample records for the topic natural composite materials from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Natural frequency behavior of damaged composite materials  

NASA Astrophysics Data System (ADS)

Attention is given to characterizing the effect of material system, geometry, and stacking sequence on the vibration response of damaged plates of fiber-reinforced composite. Plate layups are fashioned from various composite materials and subjected to four damage cycles, and a signal analyzer is employed to study the frequency response function (FRF) of the materials. The materials employed include the AS4/3501-6, IM7/E7T1-2, and IM7/977-2 families, and numerical analyses are used for comparison. Frequencies are obtained from the experimentally established FRFs, and natural frequencies tend to decrease in the presence of extensive localized damage. The fiber is argued to dominate the response of the plate, and the experimental data are confirmed in some cases by the results of finite-element calculations.

Duggan, M. B.; Ochoa, O. O.

1992-11-01

2

Study of the Nature of Fracture Failure in Composite Materials.  

National Technical Information Service (NTIS)

The boron, aluminum composite material samples were cut to shape and subjected to push-pull type of loading under Instron Servo Hydrolic test system to failure. The failure surfaces were examined under electron microscope. The data collected under about t...

R. N. Rao

1986-01-01

3

Use of natural particles for the removal of paint from aeronautical composite materials  

Microsoft Academic Search

Paint removal by blasting and its effects on the surface morphology of aeronautical composite materials are investigated. An ideal combination of the parameters for mechanical paint removal by blasting such as particle type, size, velocity and angle of incidence yields a stripped aircraft skin substrate with minimal or no damage. Natural particles, specifically white corn flour, seem to be a

Thu-Ha Guy; Hamid M. Lankarani; Jorge E. Talia

1991-01-01

4

Composite material  

DOEpatents

A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O' Neill, Hugh M. (Knoxville, TN)

2012-02-07

5

Composite material  

SciTech Connect

A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O'Neill, Hugh M. (Knoxville, TN)

2012-02-07

6

Use of natural particles for the removal of paint from aeronautical composite materials  

NASA Astrophysics Data System (ADS)

Paint removal by blasting and its effects on the surface morphology of aeronautical composite materials are investigated. An ideal combination of the parameters for mechanical paint removal by blasting such as particle type, size, velocity and angle of incidence yields a stripped aircraft skin substrate with minimal or no damage. Natural particles, specifically white corn flour, seem to be a good choice for paint removal by blasting. Since they are softer as well as smaller in size than other particles used for paint removal, they minimize the amount of damage to the surface of the composite. They are also cheaper and produce no harm to environment. The variation of the degree of surface roughness and the amount of broken fibers were correlated with some stripping parameters, such as particle impact angle and velocity. This defined an optimum environment for paint removal by blasting.

Guy, Thu-Ha; Lankarani, Hamid M.; Talia, Jorge E.

7

Production of natural and synthesized aluminum-based composite materials with the aid of ultrasonic (cavitation) treatment of the melt.  

PubMed

The application of ultrasonic melt treatment to the production of natural and synthesized aluminum-based composite materials is considered in terms of underlying basic ideas and commercial implementations. It is shown that the ultrasonic cavitation treatment combined with microalloying of hypereutectic Al-Si natural composites (alloys) promotes the formation of structures suitable for further deformation. The use of highly impure starting materials becomes also possible. The combination of ultrasonic cavitation treatment with electromagnetic stirring allows one to considerably improve the size and spatial distribution of ceramic particles in metal-matrix composites. PMID:12818397

Eskin, G I; Eskin, D G

2003-07-01

8

Effect of Paint Removal by Natural Bead Blasting on the Surface Morphology of Composite Materials.  

National Technical Information Service (NTIS)

The purpose of the study was to investigate paint removal by blasting and its effects on the surface morphology of the composite materials. Plastic media blasting (PMB), used extensively by many as a paint removal method, showed potential microstructural ...

T. H. Guy H. Lankarani J. E. Talia

1990-01-01

9

Overview and Advances on Science, Technology and Application of Composite Materials based on Natural Resources  

Microsoft Academic Search

Materials based on natural resources are enjoying revived interest in their applications. They have the potential for lightweight designs, which by being able to reduce materials use and possibly the cost as well, contribute towards sustainable product development, which can be considered as an optimal combination of technical, economic as well as ecological feasibilities. Materials of renewable resources can provide

P. V. Kandachar

10

Composite Materials Handbook  

NSDL National Science Digital Library

From the US Army Research Laboratory, Materials Sciences Corporation, and University of Delaware Center for Composite Materials, the Composite Materials Handbook provides the "information and guidance necessary to design and fabricate end items from composite materials." Along with current information on the material properties of these composite materials, the handbook also includes data development and usage guidelines. The information has been divided into three areas: polymer, metal, and ceramic matrix composites. The Polymer Matrix Composites Handbook (three volumes including Guidelines for Characterization of Structural Materials; Material Properties; and Materials Usage, Design, and Analysis) and the Metal Matrix Composites Handbook (one volume, .pdf) are available here. The Ceramic Matrix Composites Handbook has yet to be completed. Users may also download Quick Composites Data in spreadsheet format.

11

Composite Structural Materials.  

National Technical Information Service (NTIS)

The promise of filamentary composite materials, whose development may be considered as entering its second generation, continues to generate intense interest and applications activity. Fiber reinforced composite materials offer substantially improved perf...

G. S. Ansell R. G. Loewy S. E. Wiberley

1982-01-01

12

Composite materials and their use in structures  

Microsoft Academic Search

This book attempts to provide a basic fundamental understanding of the physical and mathematical aspects of the materials system and structures comprised of composite materials. The introduction discusses the nature and scope of composite materials, the strengthening processes used in the manufacture of alloys, and the needs for composite materials. Then various types of fiber-reinforced materials are examined, first by

J. R. Vinson; T. W. Chou

1975-01-01

13

Mechanics of composite materials  

SciTech Connect

This book contains the following papers: crack growth resistance of TiB{sub 2} particulate/SiC matrix composite; constitutive relations of flexible composites under elastic deformation; determination of two kinds of composite plasticity: inclusions plastic vs. matrix plastic; 3-D analysis of transient interlaminar thermal stress of laminated composites; effect of seawater on the fracture toughness of pultruded rods; evaluation of new failure criterion for fibrous composite materials; and bridged cracks in fiber-reinforced composites.

Dvorak, G.J. (Inst. Center for Composite Materials and Structures, Rensselaer Polytechnic Inst. (US)); Laws, N. (Dept. of Mechanical Engineering, Univ. of Pittsburgh, PA (US))

1988-01-01

14

Electrically conductive composite material  

DOEpatents

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

Clough, Roger L. (Albuquerque, NM); Sylwester, Alan P. (Albuquerque, NM)

1989-01-01

15

Composite Material Switches  

NASA Astrophysics Data System (ADS)

A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

Javadi, Hamid

2002-09-01

16

Resin composite restorative materials.  

PubMed

This paper surveys the most important developments in resin-based dental composites and focuses on the deficits (e.g. polymerization shrinkage) and strengths of the materials and their clinical implications. Moreover, differences between composite categories, such as hybrid, nanohybrid, microfilled, packable, ormocer-based, silorane-based, polyacid-modified composites (compomers) and flowable composites are highlighted, especially in view of their mechanical behaviour. In addition to the classical dimethacrylate-based composites, special attention is given to alternative monomers, such as siloranes, ormocers or high-molecular-weight dimethacrylate monomers (e.g. dimer acid-based dimethacrylates and tricyclodecane (TCD)-urethane), analysing their advantages, behaviour and abilities. Finally, the paper attempts to establish the needs and wishes of clinicians for further development of resin-based composites. PMID:21564116

Ilie, N; Hickel, R

2011-06-01

17

Nanostructured composite reinforced material  

DOEpatents

A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

Seals, Roland D. (Oak Ridge, TN); Ripley, Edward B. (Knoxville, TN); Ludtka, Gerard M. (Oak Ridge, TN)

2012-07-31

18

Orthopedic Composite Materials.  

National Technical Information Service (NTIS)

The program was designed as a pilot project to establish new techniques for making orthopedic prosthetic materials. The basic idea was to make metal supported ceramic composites, so that the metal provided strength (and an element of ductility) and the re...

B. J. Shaw

1972-01-01

19

An analysis of the abaca natural fiber in reinforcing concrete composites as a construction material in developing countries  

Microsoft Academic Search

This study analyzed the flexural and splitting tensile strengths and the ductility of abaca fiber-reinforced concrete composites. Abaca fibers are natural fibers of vegetable origin from the abaca plant native to the Philippine Islands. The purpose was to investigate how various volume-fractions of the abaca fiber could affect the mechanical properties of the concrete matrix. A concrete design mix containing

Magdamo

1988-01-01

20

Thermoplastic pultrusion of natural fibre reinforced composites  

Microsoft Academic Search

Thanks to the good mechanical properties and the ecological and environmental advantages, the natural fibre flax offers good opportunities as a reinforcement material for composites, especially thermoplastic ones. One technique for the manufacture of composites on a continuous basis is pultrusion. This paper describes the possibility of the use of flax as reinforcement in thermoplastic pultruded composites.

Kathleen Van de Velde; Paul Kiekens

2001-01-01

21

Natural Fiber Reinforced PLA Composites  

Microsoft Academic Search

We investigated the physical properties of natural fiber reinforced PLA composites, which were prepared by using PLA films and fibers. The impact, tensile, and dynamic mechanical properties of the composites were observed to examine the reinforcing effect of natural fibers. In addition, numerical analysis was carried out to more clarify the experimental results. The natural fibers\\/PLA composites shows a good

Young Seok Song; Jung Tae Lee; Jae Ryoun Youn

2010-01-01

22

Natural Fiber Reinforced PLA Composites  

Microsoft Academic Search

We investigated the physical properties of natural fiber reinforced PLA composites, which were prepared by using PLA films and fibers. The impact, tensile, and dynamic mechanical properties of the composites were observed to examine the reinforcing effect of natural fibers. In addition, numerical analysis was carried out to more clarify the experimental results. The natural fibers?PLA composites shows a good

Young Seok Song; Jung Tae Lee; Jae Ryoun Youn

2010-01-01

23

Study of the nature of fracture failure in composite materials. Final report, 1 May 1985-31 August 1986  

SciTech Connect

The boron, aluminum composite material samples were cut to shape and subjected to push-pull type of loading under Instron Servo Hydrolic test system to failure. The failure surfaces were examined under electron microscope. The data collected under about ten experiments were used for an M.S.E. thesis of one graduate student.

Rao, R.N.

1986-12-01

24

Liquid Helium Composite Regenerator Material.  

National Technical Information Service (NTIS)

A cryogenic composite material designed for application to gap regenerators in cyclic cryocoolers operating below 10 K is investigated. The material is a composite of helium self-loaded into a metallic extended surface structure whose dispersion form is s...

T. R. Knowles

1987-01-01

25

Multifunctional Autonomically Healing Composite Material.  

National Technical Information Service (NTIS)

A composite material, contains a polymer, a polymerizer, a corresponding catalyst for the polymerizer, and a plurality of capsules. The polymerizer is in the capsules. The composite material is self-healing.

J. S. Moore N. R. Sottos P. H. Geubelle S. R. Sriram S. R. White

2005-01-01

26

Composite Materials: Properties as Influenced by Phase Geometry  

Microsoft Academic Search

This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. The monograph provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the influence of geometry to materials properties. Composite Materials enables the reader to a better understanding of the behavior of natural composites, improvement of

Lauge F. Nielsen

2005-01-01

27

Energy Absorption of Composite Materials.  

National Technical Information Service (NTIS)

This paper results of a study on the energy absorption characteristics of selected composite material systems and compares the results with aluminum. Composite compression tube specimens were fabricated with both tape and woven fabric prepreg using graphi...

G. L. Farley

1983-01-01

28

Composite material heat pipe radiator  

Microsoft Academic Search

Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness

Nelson J. Gernert; David B. Sarraf; Richard J. Guenther

1996-01-01

29

Joining of composite materials  

SciTech Connect

This Conference Proceedings contains 9 papers, of which one is abstracted separately, describing the latest achievement in effective methods of joining of composite structures. Most composite systems do not deform plastically and thus cannot alleviate stress concentration. The papers cover the design, analysis, testing and inspection of joined interfaces. Data are given for both mechanically fastened and adhesively bonded joints.

Kedward, K.T.

1981-01-01

30

Natural rubber: leather composites  

Microsoft Academic Search

Leather is a fibrous protein consisting of collagen in a three dimensionally crosslinked network. Chrome tanning of leather improves the appearance of leather but at the same time emits both solid and liquid chrome leather wastes. Scrap rubber recycling using untreated and neutralized leather fibrous particles in natural rubber has been studied. Vulcanization, mechanical, morphological and swelling properties of the

K. Ravichandran; N. Natchimuthu

2005-01-01

31

Reversibly assembled cellular composite materials.  

PubMed

We introduce composite materials made by reversibly assembling a three-dimensional lattice of mass-produced carbon fiber-reinforced polymer composite parts with integrated mechanical interlocking connections. The resulting cellular composite materials can respond as an elastic solid with an extremely large measured modulus for an ultralight material (12.3 megapascals at a density of 7.2 milligrams per cubic centimeter). These materials offer a hierarchical decomposition in modeling, with bulk properties that can be predicted from component measurements and deformation modes that can be determined by the placement of part types. Because site locations are locally constrained, structures can be produced in a relative assembly process that merges desirable features of fiber composites, cellular materials, and additive manufacturing. PMID:23950496

Cheung, Kenneth C; Gershenfeld, Neil

2013-08-15

32

Natural ageing of EPDM composite insulators  

Microsoft Academic Search

Long-rod composite insulators, with weather sheds (sheds) made of ethylene propylene rubbers (EPDM), were exposed for many years to HVAC and HVDC under realistic conditions and natural pollution. The change of their properties with time and their aging was studied. The results show that the insulator shed material undergoes a slow degradation process and loses successively its water repelling properties

A. E. Vlastos; E. Sherif

1990-01-01

33

Mechanics of composite materials  

Microsoft Academic Search

The book presents a comprehensive account of the basic theory of the mechanical behavior of heterogeneous materials. Basic results of continuum mechanics concerning elasticity theory, viscoelasticity theory, plasticity theory and Eshelby's formula are summarized, and the stiffness or effective moduli of materials containing spherical inclusions and cylindrical and lamellar systems are examined in detail. Laminates are discussed, and the analysis,

R. M. Christensen

1979-01-01

34

Biotechnology and Composite Materials.  

National Technical Information Service (NTIS)

Biotechnology, in general terms, is the science and engineering of using living organisms for making useful products such as pharmaceuticals, foods, fuels, chemicals, materials or in waste treatment processes and clinical and chemical analyses. It encompa...

B. C. Woolsey R. Narayan R.C. Schiavone

1993-01-01

35

Fracture mechanics of composite materials  

Microsoft Academic Search

The above circumstances lead to models based on a discussion of the structure of a composite being used most frequently in the fracture mechanics of composite materials. In view of the stochastic properties of the elements in the structure, especially the dispersion in the strength of the fibers, stochastic fracture models are widely used [4-7]. Nevertheless, there has been no

V. V. Bolotin

1981-01-01

36

Left Handed Materials Using Magnetic Composites.  

National Technical Information Service (NTIS)

A left-handed composite material which includes a mixture of a ferromagnetic material and a dielectric material. The direction of magnetization of the ferromagnetic material, and its volume fraction are controlled such that the composite material exhibits...

J. Q. Xiao S. T. Chui

2003-01-01

37

Critical factors on manufacturing processes of natural fibre composites  

Microsoft Academic Search

Elevated environmental awareness of the general public in reducing carbon footprints and the use non-naturally decomposed solid wastes has resulted in an increasing use of natural materials, biodegradable and recyclable polymers and their composites for a wide range of engineering applications. The properties of natural fibre reinforced polymer composites are generally governed by the pre-treated process of fibre and the

Mei-po Ho; Hao Wang; Joong-Hee Lee; Chun-kit Ho; Kin-tak Lau; Jinsong Leng; David Hui

38

Ski Technology And Composite Materials  

NSDL National Science Digital Library

The following resource is from Lessonopoly, which has created student activities and lesson plans to support the video series, Science of the Olympic Winter Games, created by NBC Learn and the National Science Foundation. Featuring exclusive footage from NBC Sports and contributions from Olympic athletes and NSF scientists, the series will help teach your students valuable scientific concepts. Students will learn the basic engineering issues related to ski design. They will learn about composite materials and polymer materials. Also, students will create and test a composite material.

2010-01-01

39

Dense, finely, grained composite materials  

DOEpatents

Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

Dunmead, Stephen D. (Davis, CA); Holt, Joseph B. (San Jose, CA); Kingman, Donald D. (Danville, CA); Munir, Zuhair A. (Davis, CA)

1990-01-01

40

Dense, finely grained composite materials  

DOEpatents

Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected. 10 figs.

Dunmead, S.D.; Holt, J.B.; Kingman, D.D.; Munir, Z.A.

1988-10-21

41

Mechanical properties of natural fibre-reinforced composites  

Microsoft Academic Search

Natural fibres were initially used in composite materials to predominately improve bulk and reduce cost rather than improving mechanical properties. But the environmental problems associated with the production and use of synthetic fibres have changed the scenario. In the previous decade, natural fibres have been extensively used as reinforcement materials for both synthetic and bio-degradable matrices. Natural fibre reinforcements have

Manik Bhowmick; Samrat Mukhopadhyay; Ramasamy Alagirusamy

2012-01-01

42

Hydrogel Composite Materials for Tissue Engineering Scaffolds  

NASA Astrophysics Data System (ADS)

Hydrogels are appealing for biomaterials applications due to their compositional similarity with highly hydrated natural biological tissues. However, for structurally demanding tissue engineering applications, hydrogel use is limited by poor mechanical properties. Here, composite materials approaches are considered for improving hydrogel properties while attempting to more closely mimic natural biological tissue structures. A variety of composite material microstructures is explored, based on multiple hydrogel constituents, particle reinforcement, electrospun nanometer to micrometer diameter polymer fibers with single and multiple fiber networks, and combinations of these approaches to form fully three-dimensional fiber-reinforced hydrogels. Natural and synthetic polymers are examined for formation of a range of scaffolds and across a range of engineered tissue applications. Following a discussion of the design and fabrication of composite scaffolds, interactions between living biological cells and composite scaffolds are considered across the full life cycle of tissue engineering from scaffold fabrication to in vivo use. We conclude with a summary of progress in this area to date and make recommendations for continuing research and for advanced hydrogel scaffold development.

Shapiro, Jenna M.; Oyen, Michelle L.

2013-04-01

43

Composite containing coated fibrous material  

SciTech Connect

This patent describes a process for producing a composite containing at least about 10% by volume of boron nitride coated fibrous material and having a porosity of less than about 20% by volume. It comprises: forming a slurry of infiltration-promoting material and organic binding material in a liquid medium; depositing a coating of boron nitride on fibrous material leaving no significant portion thereof exposed; depositing a silicon-wettable coating on the boron nitride-coated fibrous material leaving no significant portion of the boron nitride exposed; providing the resulting coated fibrous material substantially as a layer; casting the slurry onto the coated fibrous material in an amount sufficient to form a tape therewith; evaporating the liquid medium forming a tape; firing the tape to remove the organic binding material producing a porous body; providing an infiltrant comprised of boron and silicon containing elemental boron in solution in silicon in an amount of at least about 0.1% by weight of elemental silicon; contacting the porous body with infiltrant associated infiltrating means whereby the infiltrant is infiltrated into the porous body; heating the resulting assembly in a partial vacuum to a temperature at which the infiltrant is molten and infiltrating the molten infiltrant into the porous body to produce an infiltrated product; and cooling the product producing the composite.

Singh, R.N.; Gaddipati, A.R.

1989-12-26

44

Joining of polymer composite materials  

SciTech Connect

Under ideal conditions load bearing structures would be designed without joints, thus eliminating a source of added weight, complexity and weakness. In reality the need for accessibility, repair, and inspectability, added to the size limitations imposed by the manufacturing process and transportation/assembly requirements mean that some minimum number of joints will be required in most structures. The designer generally has two methods for joining fiber composite materials, adhesive bonding and mechanical fastening. As the use of thermoplastic materials increases, a third joining technique -- welding -- will become more common. It is the purpose of this document to provide a review of the available sources pertinent to the design of joints in fiber composites. The primary emphasis is given to adhesive bonding and mechanical fastening with information coming from documentary sources as old as 1961 and as recent as 1989. A third, shorter section on composite welding is included in order to provide a relatively comprehensive treatment of the subject.

Magness, F.H.

1990-11-01

45

Modern Carbon Composite Brake Materials  

Microsoft Academic Search

Carbon-carbon composites used in friction systems are becoming increasingly popular in aircrafts owing to their combination of low weight and high performance. Their current acceptance as brake materials is somewhat restrained due to two factors: cost and performance variations. Many manufacturers are taking steps toward improving their cost efficiency by utilizing lower cost precursor fibers and processing methodologies. At the

Christopher Byrne

2004-01-01

46

Durability of polymer composite materials  

Microsoft Academic Search

The purpose of this research is to examine structural durability of advanced composite materials under critical loading conditions, e.g., combined thermal and mechanical loading and shear fatigue loading. A thermal buckling model of a burnt column, either axially restrained or under an axial applied force was developed. It was predicted that for a column exposed to the high heat flux

Liu Liu

2006-01-01

47

Welds in thermoplastic composite materials  

NASA Astrophysics Data System (ADS)

Welding methods are reviewed that can be effectively used for joining of thermoplastic composites and continuous-fiber thermoplastics. Attention is given to the use of ultrasonic, vibration, hot-plate, resistance, and induction welding techniques. The welding techniques are shown to provide complementary weld qualities for the range of thermoplastic materials that are of interest to industrial and technological applications.

Taylor, N. S.

48

Properties of Five Toughened Matrix Composite Materials.  

National Technical Information Service (NTIS)

The use of toughened matrix composite materials offers an attractive solution to the problem of poor damage tolerance associated with advanced composite materials. In this study, the unidirectional laminate strengths and moduli, notched (open-hole) and un...

R. J. Cano M. B. Dow

1992-01-01

49

Composite, Ordered Material Having Sharp Surface Features.  

National Technical Information Service (NTIS)

A composite material having sharp surface features includes a recessive phase and a protrusive phase, the recessive phase having a higher susceptibility to a preselected etchant than the protrusive phase, the composite material having an etched surface wh...

B. R. D'Urso J. T. Simpson

2005-01-01

50

NDE of polymeric composite material bridge components  

NASA Astrophysics Data System (ADS)

Rapid advancements with respect to utilization of polymeric composite materials for bridge components is occurring. This situation is driven primarily by the potential improvements offered by these materials with respect to long term durability. However, because of the developmental nature of these materials much of the materials characterization has involved short term testing without the synergistic effects of environmental exposure. Efforts to develop nondestructive evaluation procedures, essential for any wide spread use in critical structural applications, have been consequently limited. This paper discuses the effort to develop NDE methods for field inspection of hybrid glass and carbon fiber reinforced vinyl ester pultruded 'double box' I beams that are installed in a small bridge over Tom's Creek, in Blacksburg, Virginia. Integrated structural element sensors, dormant infrared devices, as well as acousto-ultrasonic methods are under development for detecting and monitoring the occurrence and progression of life limiting deterioration mechanisms.

Duke, John C.; Horne, Michael R.

1998-03-01

51

Investigation of the Role of the Interface in Composite Materials.  

National Technical Information Service (NTIS)

The role of the interface in composite materials has been investigated to determine the nature of bonding between matrix and dispersed constituents and the manner in which these bonds across the interface actually give rise to the resultant properties of ...

M. H. Richman R. D. French

1968-01-01

52

A RESEARCH REVIEW ARTICLE ON COMPOSITE MATERIAL  

PubMed Central

The search of aesthetic dental material is on. Composites are a material of choice in this category. Composite have developed over past few years and increased use of material is in demand. This article gives us a brief knowledge of existing and newer composites.

CHOKSI, DIPTI; IDNANI, BARKHA

2013-01-01

53

Sunflower cake as a natural composite: composition and plastic properties.  

PubMed

Nowadays, the end-of-life of plastic products and the decrease of fossil energy are great environmental problems. Moreover, with the increase of food and nonfood transformations of renewable resources, the quantities of agro-industrial byproducts and wastes increase hugely. These facts allow the development of plastic substitutes made from agro-resources. Many researches show the feasibility of molding biopolymers extracted from plants like a common polymeric matrix. Other natural macromolecules are used like fillers into polyolefins, for example. However, limited works present results about the transformation of a natural blend of biopolymers into a plastic material. The aim of this study is the determination of the composition of sunflower cake (SFC) and also the characterization of its components. These were identified by chemical and biochemical analysis often used in agricultural or food chemistry. Most of the extraction and purification processes modify the macrostructure of several biopolymers (e.g., denaturation of proteins, cleavage or creation of weak bonds, etc.). So, the composition of different parts of the sunflower seed (husk, kernel, and also protein isolate) was determined, and the plasticlike properties of their components were studied with thermogravimetric analysis, differential scanning calorimetry, and a dynamic mechanical thermal analysis apparatus. Finally, this indirect way of characterization showed that SFC can be considered a natural composite. In SFC, several components like lignocellulosic fibers [40%/dry matter (DM)], which essentially come from the husk of sunflower seed, can act as fillers. However, other biopolymers like globulins ( approximately 30% of the 30% of sunflower seed proteins/DM of SFC) can be shaped as a thermoplastic-like material because this kind of protein has a temperature of glass transition and a temperature of denaturation that seems to be similar to a melting temperature. These proteins have also viscoelastic properties. Moreover, SFC has similar rheological properties and other physicochemical properties compatible with shaping or molding behaviors of plastic-processing machinery. PMID:18998703

Geneau-Sbartaï, Céline; Leyris, Juliette; Silvestre, Françoise; Rigal, Luc

2008-12-10

54

Composite material heat pipe radiator  

SciTech Connect

Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness (0.076 mm). The thin liner transitioned to heavier-walled ends which allowed the tubing to be sealed using conventional welding. More specifically, the heat pipe was 1.14 m long, 24 mm in diameter and had a mass of 0.165 kg. Water was the working fluid. The heat pipe was tested in a Thermacore thermal vacuum chamber under hot and cold wall operating conditions. The heat load dissipated ranged from 10 to 60 watts. Heat pipe operating temperatures varied from 278 K to 403 K. After testing, the heat pipe was delivered to NASA JSC where future thermal vacuum chamber tests are planned. {copyright} {ital 1996 American Institute of Physics.}

Gernert, N.J.; Sarraf, D.B. [Thermacore, Inc., 780 Eden Road, Lancaster, Pennsylvania 17601 (United States); Guenther, R.J. [Battelle, Pacific Northwest Laboratories, Richland, Washington 99352 (United States); Hurlbert/, K.M. [NASA Johnson Space Center, 2101 NASA Road, 1 Houston, Texas 77058-3696 (United States); EC3

1996-03-01

55

Self-healing polymer composites: mimicking nature to enhance performance  

Microsoft Academic Search

Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies

R S Trask; H R Williams; I P Bond

2007-01-01

56

Optimized adhesives for strong, lightweight, damage-resistant, nanocomposite materials: new insights from natural materials  

NASA Astrophysics Data System (ADS)

From our investigations of natural composite materials such as abalone shell and bone we have learned the following. (1) Nature is frugal with resources: it uses just a few per cent glue, by weight, to glue together composite materials. (2) Nature does not avoid voids. (3) Nature makes optimized glues with sacrificial bonds and hidden length. We discuss how optimized adhesives combined with high specific stiffness/strength structures such as carbon nanotubes or graphene sheets could yield remarkably strong, lightweight, and damage-resistant materials.

Hansma, P. K.; Turner, P. J.; Ruoff, R. S.

2007-01-01

57

Composite materials for thermal energy storage  

DOEpatents

A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

Benson, D.K.; Burrows, R.W.; Shinton, Y.D.

1985-01-04

58

Polyolefin composites containing a phase change material  

DOEpatents

A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein, said polyolefin being thermally form stable; the composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

Salyer, Ival O. (Dayton, OH)

1991-01-01

59

Natural materials for carbon capture.  

SciTech Connect

Naturally occurring clay minerals provide a distinctive material for carbon capture and carbon dioxide sequestration. Swelling clay minerals, such as the smectite variety, possess an aluminosilicate structure that is controlled by low-charge layers that readily expand to accommodate water molecules and, potentially, carbon dioxide. Recent experimental studies have demonstrated the efficacy of intercalating carbon dioxide in the interlayer of layered clays but little is known about the molecular mechanisms of the process and the extent of carbon capture as a function of clay charge and structure. A series of molecular dynamics simulations and vibrational analyses have been completed to assess the molecular interactions associated with incorporation of CO2 in the interlayer of montmorillonite clay and to help validate the models with experimental observation.

Myshakin, Evgeniy M. (National Energy Technology Laboratory, Pittsburgh, PA); Romanov, Vyacheslav N. (National Energy Technology Laboratory, Pittsburgh, PA); Cygan, Randall Timothy

2010-11-01

60

Thin film dielectric composite materials  

DOEpatents

A dielectric composite material comprising at least two crystal phases of different components with TiO.sub.2 as a first component and a material selected from the group consisting of Ba.sub.1-x Sr.sub.x TiO.sub.3 where x is from 0.3 to 0.7, Pb.sub.1-x Ca.sub.x TiO.sub.3 where x is from 0.4 to 0.7, Sr.sub.1-x Pb.sub.x TiO.sub.3 where x is from 0.2 to 0.4, Ba.sub.1-x Cd.sub.x TiO.sub.3 where x is from 0.02 to 0.1, BaTi.sub.1-x Zr.sub.x O.sub.3 where x is from 0.2 to 0.3, BaTi.sub.1-x Sn.sub.x O.sub.3 where x is from 0.15 to 0.3, BaTi.sub.1-x Hf.sub.x O.sub.3 where x is from 0.24 to 0.3, Pb.sub.1-1.3x La.sub.x TiO.sub.3+0.2x where x is from 0.23 to 0.3, (BaTiO.sub.3).sub.x (PbFeo.sub.0.5 Nb.sub.0.5 O.sub.3).sub.1-x where x is from 0.75 to 0.9, (PbTiO.sub.3).sub.- (PbCo.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.1 to 0.45, (PbTiO.sub.3).sub.x (PbMg.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.2 to 0.4, and (PbTiO.sub.3).sub.x (PbFe.sub.0.5 Ta.sub.0.5 O.sub.3).sub.1-x where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

Jia, Quanxi (Los Alamos, NM); Gibbons, Brady J. (Los Alamos, NM); Findikoglu, Alp T. (Los Alamos, NM); Park, Bae Ho (Los Alamos, NM)

2002-01-01

61

Flexure Tests of Three Fibrous Composite Materials.  

National Technical Information Service (NTIS)

Carbon and glass/ester composites were tested for flexural stiffness and strength. The test specimens were prepared from three types of composite materials: carbon fiber cloth/vinylester, glassfiber cloth/vinylester, and glassfiber/polyester in prepreg fo...

L. Knutsson H. Bjermert

1980-01-01

62

Composite, Nanostructured, Super-Hydrophobic Material.  

National Technical Information Service (NTIS)

A hydrophobic disordered composite material having a protrusive surface feature includes a recessive phase and a protrusive phase, the recessive phase having a higher susceptibility to a preselected etchant than the protrusive phase, the composite materia...

B. R. D'Urso J. T. Simpson

2005-01-01

63

Lignins as Components of Polymeric Composite Materials  

NASA Astrophysics Data System (ADS)

The results of studies of natural, native, and technical lignins are surveyed. Data are presented on the structures and physicochemical properties of various technical lignins (hydrolytic, sulphite, and sulphate lignins), which constitute the waste of the cellulose-paper and hydrolytic industries. Considerable attention is devoted to the examination of the properties of lignins which are responsible for their employment for the reinforcement of elastomers and the modification of plastics. The methods of utilisation and rational employment of technical lignins in the plastics industry as active ingredients of polymeric composite materials are examined. The importance of sulphate lignins as the most active from the standpoint of structure and properties in relation to the polymer matrix for the creation of highly filled lignin-containing polymeric materials — lignoplastics of the type of poprolin — is specially emphasised. The bibliography includes 160 references.

Lyubeshkina, E. G.

1983-07-01

64

Optical sensor using functionalized composite materials  

US Patent & Trademark Office Database

The invention relates to a method for sensing the presence of at least one analyte in a medium, comprising disposing in the medium a functionalized composite material such that the at least one analyte is absorbed by the functionalized composite material, the functionalized composite material having at least one optical property that is modulated by absorption of the at least one analyte; and measuring modulation of the at least one optical property of the functionalized composite material; wherein modulation of the at least one optical property of the functionalized composite material is indicative of the presence of the analyte in the medium. The invention also relates to an optical sensor for sensing the presence of at least one analyte in a medium, and a functionalized composite material having at least one optical property that is modulated upon absorption of one or more analyte.

2010-08-17

65

The nature of cometary materials  

NASA Astrophysics Data System (ADS)

Because cometary surfaces are likely to be far colder and of a different composition than planetary surfaces, there are some new considerations that must be examined in regards to placing instrumented packages or sample return devices on their surfaces. The qualitative analysis of the problem of attaching hardware to a comet and not being ejected back into space can be divided into two parts. The first problem is to pierce the mantle and obtain access to the icy core. Drilling through the mantle requires that the drilling forces be reacted. Reacting such forces probably requires attachment to the icy core below. Therefore, some kinetic impact piercing device is likely to be required as the first act of attachment. The second problem for a piercing device to overcome is the force produced by the impact kinetic energy that tries to eject the piercing device back into space. The mantle and icy core can absorb some of the impact kinetic energy in the form of fracture formation and friction energy. The energy that is not absorbed in these two ways is stored by the core as elastic deformation of the mantle and icy core. It is concluded that because the cometary materials are almost certainly brittle and the icy core is likely to be self lubricating, the elastic rebound and gas pressure expulsion forces must be counteracted by forces greater than those that may be provided by a piercing device or its capture devices (barbs).

Stephens, James

66

Dynamic compaction of particulate composite materials  

NASA Astrophysics Data System (ADS)

This paper describes the mechanical alloying + dynamic compaction flowchart for producing composites with particulate reinforcements. The combinations of components tested included aluminum silicon carbide, aluminum boron carbide, copper silicon carbide, and copper silica. Mechanical alloying produced granules of composite with reinforcements uniformly distributed in the matrix material. Dynamic compaction of mechanically alloyed granules was shown to produce high quality composite materials with crack-free structure. As the standard methods for explosive treatment lead to crack formation in bulk composites, this work included the development of a tool for treating composite materials.

Popov, V. A.; Staudhammer, K. P.; Goulbin, V. N.

2006-08-01

67

Surface composition of natural satellites  

Microsoft Academic Search

Current knowledge regarding the surface composition of solar system satellites is reviewed. It is noted that reflectance spectroscopy is the most commonly used method for determining surface composition. It is found that the surface of the moon is made up primarily of basaltic and anorthositic rocks and glasses with no abundant volatiles. The surfaces of the satellites of Mars probably

Roger N. Clark; Fraser P. Fanale; Michael J. Gaffey

1986-01-01

68

Explorations in the application of nanotechnology to improve the mechanical properties of composite materials  

Microsoft Academic Search

This thesis presents the research achievements on the design, preparation, characterization, and analysis of a series of composite materials. By studying the interface interaction of the composite materials using nanotechnology, we developed composite materials that achieve satisfactory mechanical properties in two classes of materials. Durable press (DP) natural textiles are important consumer products usually achieved by erosslinking the molecules in

Cheng Yang

2007-01-01

69

Cd Isotopic Composition Measured by Plasma Source Mass Spectrometry on Natural and Anthropogenic Materials. A Preliminary Outline of Cd Isotope Systematics  

NASA Astrophysics Data System (ADS)

Cadmium is a trace metal that is used as a geochemical tracer of natural processes, like biological productivity and paleoproductivity, and also of anthropogenic pollution, as Cd is known to be a toxic heavy metal that has become a major environmental and health concern. For these purposes, an outstanding issue is to determine whether Cd, like a number of metallic elements (e.g. Fe, Cu, Zn, Mo, Tl), may display variable isotopic compositions in natural and/or industrial compounds. It is known that Cd may display variable isotopic composition. Indeed, isotopic fractionation processes have been documented in some meteorites and in lunar soils. Consequently, due to its relatively low boiling point (767\\deg C) and also to the large mass range covered by its isotopes (10 mass units), Cd might fractionate isotopically, for example during the outpouring of acidic volcanic magmas and/or the emplacement of granitoids. On another hand, isotopic fractionation could also occur during human activities like refuse incineration or industrial manufacturing, for instance. Finally, biologically-induced isotopic fractionation should not be ruled out, as it is clearly evidenced for other metals, like Fe. A high precision method has been developed for determining the isotopic composition of Cd by plasma source mass spectrometry (Neptune). This method holds on the standard-bracketing technique, owing to the availability of Cd solutions of known isotopic composition provided by the University of M\\H{u}nster. This allows to correct precisely for mass fractionation that occurs in the plasma source mass spectrometer. It is also critical for the analysis to be possible to work with Cd solutions of very high purity. Chemical isolation of Cd involves 3 steps, and may be also suitable for Cd isotopic measurements using solid source mass spectrometry. Preliminary results suggest that Cd is likely to fractionate during smelting activities, as indicated by measurements on mining waste. The calibration of a 110Cd-116Cd double spike is underway for absolute, true isotopic ratios to be derived. The double spike technique allows the isotopic analysis of Cd using a plasma source, but also a solid source mass spectrometer, as Cd ionizes efficiently in such mass spectrometers owing to the standard silicagel technique.

Innocent, C.

2004-05-01

70

Composite Materials with Improved Properties in Compression.  

National Technical Information Service (NTIS)

Preparation of composite materials which have high strength in compression. Scientific approach is to prepare novel polymeric coupling agents. These will permit formation of multiple flexible covalent bonds between fibers as well as to matrix materials. I...

W. P. Weber

1993-01-01

71

Overview of bacterial cellulose composites: A multipurpose advanced material.  

PubMed

Bacterial cellulose (BC) has received substantial interest owing to its unique structural features and impressive physico-mechanical properties. BC has a variety of applications in biomedical fields, including use as biomaterial for artificial skin, artificial blood vessels, vascular grafts, scaffolds for tissue engineering, and wound dressing. However, pristine BC lacks certain properties, which limits its applications in various fields; therefore, synthesis of BC composites has been conducted to address these limitations. A variety of BC composite synthetic strategies have been developed based on the nature and relevant applications of the combined materials. BC composites are primarily synthesized through in situ addition of reinforcement materials to BC synthetic media or the ex situ penetration of such materials into BC microfibrils. Polymer blending and solution mixing are less frequently used synthetic approaches. BC composites have been synthesized using numerous materials ranging from organic polymers to inorganic nanoparticles. In medical fields, these composites are used for tissue regeneration, healing of deep wounds, enzyme immobilization, and synthesis of medical devices that could replace cardiovascular and other connective tissues. Various electrical products, including biosensors, biocatalysts, E-papers, display devices, electrical instruments, and optoelectronic devices, are prepared from BC composites with conductive materials. In this review, we compiled various synthetic approaches for BC composite synthesis, classes of BC composites, and applications of BC composites. This study will increase interest in BC composites and the development of new ideas in this field. PMID:24053844

Shah, Nasrullah; Ul-Islam, Mazhar; Khattak, Waleed Ahmad; Park, Joong Kon

2013-08-15

72

Self-sensing structural composite materials  

Microsoft Academic Search

Self-sensing was attained in lightweight structural composite materials, including those with polymer (epoxy), carbon and ceramic (Si3N 4) matrices. Either a volume of the composite or the interlaminar interface in the composite was used as the sensor. The use of the interlaminar interface as a sensor is a new approach, which was found to be effective in continuous carbon fiber

Shoukai Wang

2002-01-01

73

Material flows vs. `natural capital'  

Microsoft Academic Search

In the discourse about sustainable development, `constant natural capital' is frequently referred to as a criterion for ecological sustainability. But what is `natural capital'? The concept will be analyzed by presenting arguments in favour of using the term and different versions of sustainability (strong and weak). Subsequently, a critique of the `natural capital' concept is brought forward, from an ecological

Friedrich Hinterberger; Fred Luks; Friedrich Schmidt-Bleek

1997-01-01

74

The interaction between lining materials and composite resin restorative materials.  

PubMed

The effects of four lining materials, Dycal, Procal, Cavitec and Poly F cement on Adaptic and Concise have been investigated in vitro. The parameters studied were surface roughness, hardness and colour both with and without an intermediate (or bonding) resin being present between the restorative material and the liner. The effects of the four liners on the composites varied both between the lining materials themselves and with the composite resin. Two materials, Procal and Dycal, had little interaction with the composites, provided an intermediate resin was used with the latter. Cavitec appeared to have an adverse reaction with the composites and Poly F, whilst having no effect on the colour of the composites, did increase surface roughness. The adverse effects of linig materials were ascribed to minor constituents, particularly methyl salicylate, present in the formulation. PMID:6453213

Lingard, G L; Davies, E H; Von Fraunhofer, J A

1981-03-01

75

Stress distribution in antifriction composite materials  

Microsoft Academic Search

The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high

L. V. Zabolotnyi

1979-01-01

76

Electromagnetic shielding effectiveness of composite material  

Microsoft Academic Search

The purpose of this paper is to present an engineering study of the electromagnetic shielding effectiveness of composite materials used in space applications. The objective of the study is to identify and quantify the important electrical characteristics of composite materials proposed as substitutes for conventional metal-based structural elements of spacecraft. Current design practices utilized by various developers of spacecraft, particularly

Patrick J. Serna; Gary H. Liechty

1999-01-01

77

Structure and properties of hybrid composite materials  

NASA Astrophysics Data System (ADS)

The structure and interfacial interaction are studied in the hybrid aluminum-matrix composite materials fabricated by reactive casting combined with mechanical mixing of fillers with a metallic melt. The following types of hardening are considered: hardening by ceramic particles and by the phases formed as isolated inclusions or coatings on ceramic particles during in situ reactions. The hardness and tribological properties of the composite materials as functions of their compositions are discussed.

Chernyshova, T. A.; Kobeleva, L. I.; Bolotova, L. K.; Katin, I. V.

2013-03-01

78

Composite Dielectric Materials for Electrical Switching  

SciTech Connect

Composites that consist of a dielectric host containing a particulate conductor as a second phase are of interest for electrical switching applications. Such composites are "smart" materials that can function as either voltage or current limiters, and the difference in fimction depends largely upon whether the dielectric is filled to below or above the percolation threshold. It also is possible to combine current and voltage limiting in a single composite to make a "super-smart" material.

Modine, F.A.

1999-04-25

79

Latent heat nano composite building materials  

Microsoft Academic Search

Heat storage for heating and cooling of buildings reduces the conventional energy consumption with a direct impact on CO2 emissions. The goal of this study was to find the physico-chemical fundamentals for tailoring phase change material (PCM)-epoxy composites as building materials depending on phase change temperature and latent heat using the optimal geometry for each application. Thus, some nano-composite materials

M. Constantinescu; L. Dumitrache; D. Constantinescu; E. M. Anghel; V. T. Popa; A. Stoica; M. Olteanu

2010-01-01

80

Composition of Natural Fresh Air  

Microsoft Academic Search

Experiments are described which are designed to examine the organic vapor content of three fresh natural atmospheres. Efforts are made to determine whether or not they are comparable to each other in vapor concentration levels and\\/or in types of organic compounds present in vapor form. The sites selected were: the Mount Washington Observatory, Gorham, New Hampshire; the US Coast Guard

Amos Turk; Claude J. D’angio

1962-01-01

81

Composition of estuarine colloidal material: organic components  

NASA Astrophysics Data System (ADS)

Colloidal material in the size range 1.2 nm to 0.4 ?m was isolated by ultrafiltration from Chesapeake Bay and Patuxent River waters (U.S.A.). Temperature controlled, stepwise pyrolysis of the freeze-dried material, followed by gas chromatographic-mass spectrometric analyses of the volatile products indicates that the primary organic components of this polymer are carbohydrates and peptides. The major pyrolysis products at the 450°C step are acetic acid, furaldehydes, furoic acid, furanmethanol, diones and lactones characteristic of carbohydrate thermal decomposition. Pyrroles, pyridines, amides and indole (protein derivatives) become more prevalent and dominate the product yield at the 600°C pyrolysis step. Olefins and saturated hydrocarbons, originating from fatty acids, are present only in minor amounts. These results are consistent with the composition of Chesapeake phytoplankton (approximately 50% protein, 30% carbohydrate, 10% lipid and 10% nucleotides by dry weight). The pyrolysis of a cultured phytoplankton and natural particulate samples produced similar oxygen and nitrogencontaining compounds, although the proportions of some components differ relative to the colloidal fraction. There were no lignin derivatives indicative of terrestrial plant detritus in any of these samples. The data suggest that aquatic microorganisms, rather than terrestrial plants, are the dominant source of colloidal organic material in these river and estuarine surface waters.

Sigleo, Anne C.; Hoering, Thomas C.; Helz, George R.

1982-09-01

82

Load-bearing natural fiber composite cellular beams and panels  

Microsoft Academic Search

Natural fiber composites, or biocomposites, have recently gained much attention due to their low cost, environmental friendliness, and their potential to compete with glass-fiber composites. The reported study demonstrates that biocomposites can be used for load-bearing components by improving their structural efficiency through cellular material arrangements. Laboratory-scale periodic cellular beams and plates were made from industrial hemp and flax fibers

Rigoberto Burgueño; Mario J. Quagliata; Amar K. Mohanty; Geeta Mehta; Lawrence T. Drzal; Manjusri Misra

2004-01-01

83

Optical Characterization of Semiconducting Natural Rubber Nanoparticles and its Composites  

NASA Astrophysics Data System (ADS)

The present work explains optical properties of semiconducting natural rubber nanoparticles from pristine natural rubber by doping. The studies give evidence that the SbCl5 is an efficient dopant for natural rubber. The mechanism of conduction predominantly involves the formation of conjugated sequence of unsaturated double bond in the polymer backbone. Examination of the UV/Vis study reveals the formation of charge transfer complexes in the polymer back bone. Particle filled elastomeric composites have become attractive owing to their low cost and widespread industrial applications. The arrival of nanometer fillers to polymer materials is a promising channel for their property modification. Natural rubber composite is prepared by mixing the pristine natural rubber with semiconducting natural rubber powder.

Neena, P.; Mathew, Anisha Mary

2011-10-01

84

The nature of cometary materials  

Microsoft Academic Search

Because cometary surfaces are likely to be far colder and of a different composition than planetary surfaces, there are some new considerations that must be examined in regards to placing instrumented packages or sample return devices on their surfaces. The qualitative analysis of the problem of attaching hardware to a comet and not being ejected back into space can be

James Stephens

1989-01-01

85

Spectral representation theory of graded composite materials  

NASA Astrophysics Data System (ADS)

In graded composite materials, the physical properties can vary continuously in space and it may give different physical phenomena when compared with homogeneous materials. The Bergman-Milton spectral representation is a rigorous mathematical formalism to express the effective dielectric constant of nongraded composite materials [1]. In this study, we consider a material (rather than microsture [2]) graded composites, and generalize the Bergman-Milton spectral representation to extract the spectral density function for the effective dielectric constant of this graded composite material in the frequency domain [3]. Analytic and numerical solution will be presented for graded films and graded spheres. [1] D. J. Bergman, Phys. Rev. B 14, 4304 (1976). [2] J. P. Huang, K. W. Yu, G. Q. Gu, M. Karttunen, Phys. Rev. E 67, 051405 (2003). [3] L. Gao, J. P. Huang, K.W. Yu, Eur. Phys. J. B 36, 475 (2003).

Chan, K. L.; Kwok, C. M.; Yu, K. W.

2008-03-01

86

Autophagous spacecraft composite materials for orbital propulsion  

Microsoft Academic Search

We are developing structural polymer composite materials that can be converted into fuels and combusted with oxidizers for orbital propulsion of spacecraft. We have identified candidate materials and demonstrated sustained combustion with nitrogen tetroxide (NTO) as an oxidizer. To improve reaction chemistry we have evaluated several energetic additives. Detailed material compatibility tests were conducted to identify stable combinations of structural

Prakash Joshi; Bernard L. Upschulte; Alan H. Gelb; B. David Green; Dean M. Lester; Ingvar Wallace; W. David Starrett; David W. Marshall

2002-01-01

87

Delamination Growth in Composite Materials.  

National Technical Information Service (NTIS)

The Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) specimens are employed to characterize MODE I and MODE II interlaminar fracture resistance of graphite/epoxy (CYCOM 982) and graphite/PEEK (APC2) composites. Sizing of test specimen geomet...

J. W. Gillespie L. A. Carlsson R. B. Pipes R. Rothschilds B. Trethewey

1986-01-01

88

GREEN COMPOSITES OF NATURAL RUBBER AND DEFATTED SOY FLOUR  

Technology Transfer Automated Retrieval System (TEKTRAN)

Viscoelastic properties of natural rubber (NR) composites reinforced by defatted soy flour (DSF) are investigated. DSF is an abundant renewable commodity and has a lower material cost than carbon black (CB). DSF contains soy protein, soy carbohydrate, and soy whey. Aqueous dispersion of DSF was b...

89

Manufacturing technology of the composite materials: nanocrystalline material - polymer type  

Microsoft Academic Search

Purpose: This paper presents the material and technological solution which makes it possible to obtain the nanocrystalline, ferromagnetic powder material of Fe73.5Cu1Nb3Si13.5B9 alloy after its thermal nanocrystallization with the succeeding high-energy milling. Another aspect was to develop the technology to obtain the nanocrystalline composite materials made by binding the obtained powder material with the high density low- pressures polyethylene (PEHD)

B. Zi?bowicz; D. Szewieczek; L. A. Dobrza?ski

90

A Statistical Theory of Composite Materials Strength  

Microsoft Academic Search

A statistical tensile failure theory of composite materials with uniaxially oriented fibers is proposed. In the theory, the strength of fibers is assumed to be a statistical quantity and the fibers around a broken fiber are supposed to be subjected to localized stress concentra tions. The number of broken fibers in a layer of composite as a function of average

Yuntian Zhu; Benlian Zhou; Guanhu He; Zongguang Zheng

1989-01-01

91

Carbon-Carbon Materials and Composites.  

National Technical Information Service (NTIS)

Carbon-fiber-reinforced carbon matrix (carbon-carbon) composites have received increasing emphasis over the past 15 years. These materials have been used primarily in the aerospace and automotive industries. Carbon-carbon composites can be made in a wide ...

D. D. Edie J. D. Buckley

1992-01-01

92

Self-healing structural composite materials  

Microsoft Academic Search

A self-healing fiber-reinforced structural polymer matrix composite material is demonstrated. In the composite, a microencapsulated healing agent and a solid chemical catalyst are dispersed within the polymer matrix phase. Healing is triggered by crack propagation through the microcapsules, which then release the healing agent into the crack plane. Subsequent exposure of the healing agent to the chemical catalyst initiates polymerization

M. R. Kessler; N. R. Sottos; S. R. White

2003-01-01

93

Method to fabricate layered material compositions  

SciTech Connect

A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM)

2002-01-01

94

Laser welding of discontinuously reinforced composite materials  

NASA Astrophysics Data System (ADS)

The features of metal composite materials fusion welding are examined and the main defects arising at argon-arc, electron-beam and laser welding of alloys Al-Be-Mg, Fe-Cu-Pb and Al-Pb are revealed. The defects formation mechanisms are indicated and technological welding methods of metal composite materials are developed. These methods allow to prevent defects formation and obtain the welds with required mechanical properties and quality.

Shiganov, I. N.

1999-01-01

95

Dynamic compressive behavior of thick composite materials  

Microsoft Academic Search

The effect of strain rate on the compressive behavior of thick carbon\\/epoxy composite materials was investigated. Falling weight impact and split Hopkinson pressure bar systems were developed for dynamic characterization of composite materials in compression at strain rates up to 2000 s–1. Strain rates below 10 s–1 were generated using a servohydraulic testing machine. Strain rates between 10 s–1 and

H. M. Hsiao; I. M. Daniel; R. D. Cordes

1998-01-01

96

Composite materials: composition, properties and clinical applications. A literature review.  

PubMed

Various composite materials are available today for direct restorative techniques. The most well-known materials are the hybrid composites. This technology, based on methacrylates and different types of filler coupled with silanes, has been continuously improved. Disadvantages such as polymerisation shrinkage, bacterial adhesion and side effects due to monomer release still remain. The aim of material development is to eliminate or at least reduce these negative factors by adapting the individual components of the material. With ormocers, the methacrylate has been partially replaced by an inorganic network. According to recent studies, the biocompatibility was not improved in all cases. The development of compomer was an attempt to combine the positive properties of glassionomers with composite technology. This has only partially succeeded, because the fluoride release is low. In an in-situ study, a caries protective effect could be shown at least in the first days following filling placement with concurrent extra-oral demineralisation. By replacing the chain-monomers in the composite matrix by ring-shaped molecules, a new approach to reduce polymerisation shrinkage was investigated. A new group of materials, the siloranes, has been developed. Siloranes are hydrophobic and need to be bonded to the dental hard tissue using a special adhesive system. Long-term clinical studies are still needed to prove the superiority of this new group of materials over modern hybrid composites. PMID:21243545

Zimmerli, Brigitte; Strub, Matthias; Jeger, Franziska; Stadler, Oliver; Lussi, Adrian

2010-01-01

97

Evaluation of Hybrid Composite Materials.  

National Technical Information Service (NTIS)

An examination of the available fiber prepregs clearly suggests that the higher stiffness and strength materials such as boron and graphite have higher price levels than the lower stiffness and strength prepregs such as Kevlar-49 and S-Glass. A logical ou...

S. V. Kulkarni B. W. Rosen H. C. Boehm

1975-01-01

98

3-D textile reinforcements in composite materials  

SciTech Connect

Laminated composite materials have been used in structural applications since the 1960s. However, their high cost and inability to accommodate fibers in the laminate`s thickness direction greatly reduce their damage tolerance and impact resistance. The second generation of materials--3-D textile reinforced composites--offers significant cost reduction, and by incorporating reinforcement in the thickness direction, dramatically increases damage tolerance and impact resistance. However, methods for predicting mechanical properties of 3-D textile reinforced composite materials tend to be more complex. These materials also have disadvantages--particularly in regard to crimps in the yarns--that require more research. Textile preforms, micro- and macromechanical modeling, manufacturing processes, and characterization all need further development. As researchers overcome these problems, this new generation of composites will emerge as a highly competitive family of materials. This book provides a state-of-the-art account of this promising technology. In it, top experts describe the manufacturing processes, highlight the advantages, identify the main applications, analyze methods for predicting mechanical properties, and detail various reinforcement strategies, including grid structure, knitted fabric composites, and the braiding technique. Armed with the information in this book, readers will be prepared to better exploit the advantages of 3-D textile reinforced composites, overcome its disadvantages, and contribute to the further development of the technology.

Miravete, A. [Univ. of Zaragoza (Spain)

1999-11-01

99

Nonmetallic materials and composites at low temperatures  

Microsoft Academic Search

This book presents articles by leading scientists who explore the cryogenic behavior of such materials as epoxies, polyethylenes, polymers, various composites, and glasses. Examines the thermal and dielectric properties of these materials, as well as their elasticity, cohesive strength, resistance to strain and fracturing, and applications. Topics include thermal properties of crystalline polymers; thermal conductivity in semicrystalline polymers; ultrasonic absorption

G. Hartwig; D. Evans

1982-01-01

100

Prediction of Crushing Stress in Composite Materials  

Microsoft Academic Search

A simple mathematical model for predicting the crushing stress of composite materials was derived and presented in this article. The present knowledge of fracture mechanics and strength of materials are used as the basis for the model. The fracture mechanics part of the analysis was based on energy release rate approach; the energy release rate, G, of the proposed model

S. Goh; H. Ku; S. L. Ang

2008-01-01

101

Assessing the natural variability in crop composition.  

PubMed

The number of evaluations of the nutrient composition of food and feed crops has increased over the past 15years due to the introduction of new crops using the tools of modern biotechnology. The composition of these crops has been extensively compared with conventional (non-transgenic) controls as an integral part of the comparative safety assessment process. Following guidelines outlined in the Organization of Economic Co-operation and Development (OECD) Consensus Documents, most of these studies have incorporated field trials at multiple geographies and a diverse range of commercially available varieties/hybrids that are analyzed to understand natural variability in composition due to genetic and environmental influences. Using studies conducted in the US, Argentina and Brazil over multiple growing seasons, this report documents the effect of geography, growing season, and genetic background on soybean composition where fatty acids and isoflavones were shown to be particularly variable. A separate investigation of 96 different maize hybrids grown at three locations in the US demonstrated that levels of free amino acids, sugars/polyols, and molecules associated with stress response can vary to a greater degree than that observed for more abundant components. The International Life Sciences Institute (ILSI) crop composition database has proven to be an important resource for collecting and disseminating nutrient composition data to promote a further understanding of the variability that occurs naturally in crops used for food and feed. PMID:20832442

Harrigan, George G; Glenn, Kevin C; Ridley, William P

2010-09-09

102

Advanced composite materials for optomechanical systems  

NASA Astrophysics Data System (ADS)

Polymer matrix composites (PMCs) have been well established in optomechanical systems for several decades. The other three classes of composites; metal matrix composites (MMCs), ceramic matrix composites (CMCs), and carbon matrix composites (CAMCs) are making significant inroads. The latter include carbon/carbon (C/C) composites (CCCs). The success of composites has resulted in increasing use in consumer, industrial, scientific, and aerospace/defense optomechanical applications. Composites offer significant advantages over traditional materials, including high stiffnesses and strengths, near-zero and tailorable coefficients of thermal expansion (CTEs), tailorable thermal conductivities (from very low to over twice that of copper), and low densities. In addition, they lack beryllium's toxicity problems. Some manufacturing processes allow parts consolidation, reducing machining and joining operations. At present, PMCs are the most widely used composites. Optomechanical applications date from the 1970s. The second High Energy Astrophysical Observatory spacecraft, placed in orbit in 1978, had an ultrahigh-modulus carbon fiber-reinforced epoxy (carbon/epoxy) optical bench metering structure. Since then, fibers and matrix materials have advanced significantly, and use of carbon fiber-reinforced polymers (CFRPs) has increased steadily. Space system examples include the Hubble Space Telescope metering truss and instrument benches, Upper Atmosphere Research Satellite (UARS), James Webb Space Telescope and many others. Use has spread to airborne applications, such as SOFIA. Perhaps the most impressive CFRP applications are the fifty-four 12m and twelve 7m moveable ground-based ALMA antennas. The other three classes of composites have a number of significant advantages over PMCs, including no moisture absorption or outgassing of organic compounds. CCC and CMC components have flown on a variety of spacecraft. MMCs have been used in space, aircraft, military and industrial applications. In this paper, we review key PMC, MMC, CCC, and CMC optomechanical system materials, including properties, advantages, disadvantages, applications and future developments. These topics are covered in more detail in SPIE short courses SC218 and SC1078.

Zweben, Carl

2013-09-01

103

ISOTOPIC COMPOSITIONS OF URANIUM REFERENCE MATERIALS  

SciTech Connect

Uranium isotopic compositions of a variety of U standard materials were measured at Lawrence Livermore National Laboratory and are reported here. Both thermal ionization mass spectrometry (TIMS) and multi-collector inductively couple plasma mass spectrometry (MC-ICPMS) were used to determine ratios of the naturally occurring isotopes of U. Establishing an internally coherent set of isotopic values for a range of U standards is essential for inter-laboratory comparison of small differences in {sup 238}U/{sup 235}U, as well as the minor isotopes of U. Differences of {approx} 1.3{per_thousand} are now being observed in {sup 238}U/{sup 235}U in natural samples, and may play an important role in understanding U geochemistry where tracing the origin of U is aided by U isotopic compositions. The {sup 238}U/{sup 235}U ratios were measured with a TRITON TIMS using a mixed {sup 233}U-{sup 236}U isotopic tracer to correct for instrument fractionation. this tracer was extremely pure and resulted in only very minor corrections on the measured {sup 238}U/{sup 235}U ratios of {approx} 0.03. The values obtained for {sup 238}U/{sup 235}U are: IRMM184 = 137.698 {+-} 0.020 (n = 15), SRM950a = 137.870 {+-} 0.018 (n = 8), and CRM112a = 137.866 {+-} 0.030 (n = 16). Uncertainties represent 2 s.d. of the population. The measured value for IRMM184 is in near-perfect agreement with the certified value of 137.697 {+-} 0.042. However, the U isotopic compositions of SRM950a and CRM112a are not certified. Minor isotopes of U were determined with a Nu Plasma HR MC-ICPMS and mass bias was corrected by sample/standard bracketing to IRMM184, using its certified {sup 238}U/{sup 235}U ratio. Thus, the isotopic compositions determined using both instruments are compatible. The values obtained for {sup 234}U/{sup 235}U are: SRM950a = (7.437 {+-} 0.043) x 10{sup -3} (n = 18), and CRM112a = (7.281 {+-} 0.050) x 10{sup -3} (n = 16), both of which are in good agreement with published values. The value for {sup 236}U/{sup 235}U in SRM950a was determined to be (8.48 {+-} 2.63) x 10{sup -6}, whereas {sup 236}U was not detected in CRM112a. They are currently obtaining the U isotopic composition of CRM129a. Preliminary results suggest that the {sup 238}U/{sup 235}U ratio is within error, but slightly lower than the certified value of 137.71.

Jacobsen, B; Borg, L; Williams, R; Brennecka, G; Hutcheon, I

2009-09-03

104

Interaction of pesticides with natural organic material  

USGS Publications Warehouse

Two examples of the interaction of pesticides with natural organic materials have been investigated. Sodium humate solubilizes DDT in water and humic acid strongly sorbs 2,4,5-T. These two types of interactions are indicative of the types that one would expect when any organic pesticide is applied to a natural soil-water system.

Wershaw, R. L.; Burcar, P. J.; Goldberg, M. C.

1969-01-01

105

Crack—Interface Interaction in Composite Materials  

Microsoft Academic Search

The presence of cracks has a major impact on the reliability of advanced materials, like fiber or particle reinforced composites\\u000a or laminated composites. This paper presents different aspects of the interaction between crack and interface: stress field\\u000a and fracture parameters for a crack approaching the interface and the crack deflection versus penetration for a crack with\\u000a the tip on the

Liviu Marsavina; Tomasz Sadowski

106

Gamma spectrometry calibrations with natural radioactive materials  

NASA Astrophysics Data System (ADS)

Natural radioactive materials were used for detector calibration. We found that KCl is a very suitable material for this purpose. The efficiency curve shape was derived by using ? ray lines of 214Bi normalised using a known quantity of KCl in the same geometry. The best fit was found by the least squares method. The summing correction coefficients for 214Bi are determined.

Panteli?, Gordana

1996-02-01

107

Health monitoring method for composite materials  

DOEpatents

An in-situ method for monitoring the health of a composite component utilizes a condition sensor made of electrically conductive particles dispersed in a polymeric matrix. The sensor is bonded or otherwise formed on the matrix surface of the composite material. Age-related shrinkage of the sensor matrix results in a decrease in the resistivity of the condition sensor. Correlation of measured sensor resistivity with data from aged specimens allows indirect determination of mechanical damage and remaining age of the composite component.

Watkins, Jr., Kenneth S. (Dahlonega, GA); Morris, Shelby J. (Hampton, VA)

2011-04-12

108

A physically-based abrasive wear model for composite materials  

SciTech Connect

A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.

2001-05-01

109

Modeling of laser interactions with composite materials.  

PubMed

We develop models of laser interactions with composite materials consisting of fibers embedded within a matrix. A ray-trace model is shown to determine the absorptivity, absorption depth, and optical power enhancement within the material, as well as the angular distribution of the reflected light. We also develop a macroscopic model, which provides physical insight and overall results. We show that the parameters in this model can be determined from the ray trace model. PMID:23669848

Boley, Charles D; Rubenchik, Alexander M

2013-05-10

110

Study of the compatibility between light-cured repair materials and composite materials by holographic interferometry  

Microsoft Academic Search

Based on current trends in research on techniques for repairing composite materials, this paper focuses on the compatibility between a light-cured repair material and composite materials. The repair material used in this study is intended to find applicability in techniques for repairing damaged composite materials. Test pieces of the composite material were excited by a sinusoidal acoustic source at a

Linfeng Guo; Zhimin Zhao; Mingjuan Gao

2005-01-01

111

Mechanical property evaluation of natural fiber coir composite  

SciTech Connect

The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only artificial fibers such as glass, carbon etc., have been used in fiber-reinforced plastics. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. In this connection, an investigation has been carried out to make use of coir, a natural fiber abundantly available in India. Natural fibers are not only strong and lightweight but also relatively very cheap. In the present work, coir composites are developed and their mechanical properties are evaluated. Scanning electron micrographs obtained from fractured surfaces were used for a qualitative evaluation of the interfacial properties of coir/epoxy and compared with glass fiber/epoxy. These results indicate that coir can be used as a potential reinforcing material for making low load bearing thermoplastic composites.

Harish, S. [Department of Mechanical and Aerospace Engineering, Arizona State University (United States); Michael, D. Peter [Department of Mechanical Engineering, College of Engineering, Guindy (India); Bensely, A. [Department of Mechanical Engineering, College of Engineering, Guindy (India)], E-mail: benzlee5@yahoo.com; Lal, D. Mohan [Department of Mechanical Engineering, College of Engineering, Guindy (India); Rajadurai, A. [Department of Production Engineering, Madras Institute of Technology (India)

2009-01-15

112

Interlaminar fracture and damage of composite materials  

Microsoft Academic Search

Interlaminar fracture behavior of composite materials under static and cyclic loadings was studied. The fracture energy is evaluated by compliance, beam and area methods. The comparison results show that the initial fracture energy could be evaluated either by beam or area method while the crack growth resistance could be calculated by compliance method. Increases in the critical load and fracture

1988-01-01

113

Physics in ``Polymers, Composites, and Sports Materials  

Microsoft Academic Search

The undergraduate science course described uses the themes of polymers and composites, as used in sports materials, to teach some key concepts in introductory chemistry and physics. The course is geared towards students who are interested in science, but are still completing prerequisite mathematics courses required for science majors. Each class is built around a laboratory activity. Atoms, molecules and

Eric Hagedorn; Milijana Suskavcevic

2007-01-01

114

Crashworthy capability of composite material structures  

Microsoft Academic Search

Considerable research interest has been directed towards the use of composite materials for crashworthiness applications, because they can be designed to provide impact energy absorption capabilities which are superior to those of metals when compared on a weight basis. This review draws together information from a variety of sources to compare the findings of researchers in this field.The anisotropy of

A. G Mamalis; M. Robinson; D. E. Manolakos; G. A. Demosthenous; M. B. Ioannidis; J. Carruthers

1997-01-01

115

Characterization of self-healing composite materials  

Microsoft Academic Search

Damage occurs in almost every composite material in the form of microcracks that develop in the epoxy matrix that binds the fibers together. Researchers at the University of Illinois Urbana Champaign have recently developed a method to reverse the effects of, or heal, damage in the epoxy matrix. Their in-situ self-healing system uses embedded microcapsules and a catalyst that trigger

Kevin John Ford

2006-01-01

116

Thermoplastic Composite Materials for Aerospace Applications  

NASA Astrophysics Data System (ADS)

Mechanical and thermo-physical properties of composites materials with thermoplastic matrix (PEEK/IM7, TPI/IM7 and PPS/IM7) used for aerospace applications have been analyzed as function of two different process techniques: compression molding and fiber placement process ``hot gas assisted.''

Casula, G.; Lenzi, F.; Vitiello, C.

2008-08-01

117

Damping Analysis of Sandwich Composite Materials  

Microsoft Academic Search

The article presents an analysis of the damping of sandwich composites, made of PVC foam cores and laminated skins. Damping parameters are investigated using beam test specimens and an impulse technique. Damping modeling is developed using a finite element analysis which evaluated the different energies dissipated in the material directions of the core and the layers of the skins. The

Mustapha Assarar; Abderrahim El Mahi; Jean-Marie Berthelot

2009-01-01

118

Magnetic Composite Materials and Arbitrary - Relationships  

Microsoft Academic Search

This theoretical study addresses fabricating composite conducting materials with an effective arbitrary B-H relationship in the quasi-static field approximation, exhibiting new magnetic properties. The experimental results demonstrate the possibility of having linear artificial structures with negative effective magnetic permeability. The equivalent circuital model confirms the theoretical and experimental analysis. In particular, following the circuital approach we show how to obtain

Bernardo Tellini; Mauro Bologna

2010-01-01

119

Candida albicans adhesion to composite resin materials.  

PubMed

The adhesion of Candida albicans to dental restorative materials in the human oral cavity may promote the occurrence of oral candidosis. This study aimed to compare the susceptibility of 14 commonly used composite resin materials (two compomers, one ormocer, one novel silorane, and ten conventional hybrid composites) to adhere Candida albicans. Differences in the amount of adhering fungi should be related to surface roughness, hydrophobicity, and the type of matrix. Cylindrical specimens of each material were made according to the manufacturers' instructions. Surface roughness R (a) was assessed by perthometer measurements and the degree of hydrophobicity by computerized contact angle analysis. Specimens were incubated with a reference strain of C. albicans (DMSZ 1386), and adhering fungi were quantified by using a bioluminometric assay in combination with an automated plate reader. Statistical differences were analyzed by the Kruskal-Wallis test and Mann-Whitney U test. Spearman's rank correlation coefficients were calculated to assess correlations. Median R (a) of the tested composite resin materials ranged between 0.04 and 0.23 microm, median contact angles between 69.2 degrees and 86.9 degrees . The two compomers and the ormocer showed lower luminescence intensities indicating less adhesion of fungi than all tested conventional hybrid composites. No conclusive correlation was found between surface roughness, hydrophobicity, and the amount of adhering C. albicans. PMID:18810508

Bürgers, Ralf; Schneider-Brachert, Wulf; Rosentritt, Martin; Handel, Gerhard; Hahnel, Sebastian

2008-09-23

120

Slow crack propagation in composite restorative materials.  

PubMed

The double-torsion test technique was used to study slow crack propagation in a set of dental composite resins including two glass-filled and two microfilled materials. The microstructure within each pair was the same but one of the resins was selfcured and the other photocured. The fracture behavior was dependent on the filler concentration and the presence of absorbed water. Wet materials fractured by slow crack growth in the range of crack velocity studied (10(-7) to 10(-3) m/s), and the microfilled composites, which contain a lower concentration of inorganic filler, had lower stress intensity factors (K1c) than the glass-filled composites tested. Dry specimens of the microfilled materials and the selfcured, glass-filled composite also showed unstable, stick-slip fracture behavior indicative of a crack blunting mechanism which leads to an elevation of the stress intensity factor for crack initiation over K1c for stable crack growth. The plasticizing effect of water increased the viscoelastic response of the materials measured by the slope of curves of slow crack growth. Analysis of fracture surfaces showed that cracks propagated at low velocities (10(-7) to 10(-5) m/s) by the apparent failure of the filler/matrix interfacial bond, and absorbed water affected the strength or fracture resistance of the interface. At high crack velocities the properties of the composite depend on the properties of the polymeric matrix, the filler, and the filler volume fraction, but at low velocities the interface is the controlling factor in the durability of these composites exposed to an aqueous environment. PMID:3584167

Montes-G, G M; Draughn, R A

1987-05-01

121

Mimicry of natural material designs and processes  

SciTech Connect

Biological structural materials, although composed of unremarkable substances synthesized at low temperatures, often exhibit superior mechanical properties. In particular, the quality in which nearly all biologically derived materials excel is toughness. The advantageous mechanical properties are attributable to the hierarchical, composite, structural arrangements common to biological systems. Materials scientists and engineers have increasingly recognized that biological designs or processing approaches applied to man-made materials (biomimesis) may offer improvements in performance over conventional designs and fabrication methods. In this survey, the structures and processing routes of marine shells, avian eggshells, wood, bone, and insect cuticle are briefly reviewed, and biomimesis research inspired by these materials is discussed. In addition, this paper describes and summarizes the applications of biomineralization, self-assembly, and templating with proteins to the fabrication of thin ceramic films and nanostructure devices.

Bond, G.M. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Richman, R.H. [Daedalus Associates, Inc., Mountain View, CA (United States); McNaughton, W.P. [Cornice Engineering, Durango, CO (United States)

1995-06-01

122

Accelerated aging of polymer composite bridge materials  

NASA Astrophysics Data System (ADS)

Accelerated aging research on samples of composite materials and candidate UV protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory. Durability results and sensor data form test with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards and acceptance criteria for PMC bridges for use in the transportation infrastructure.

Carlson, Nancy M.; Blackwood, Larry G.; Torres, Lucinda L.; Rodriguez, Julio G.; Yoder, Timothy S.

1999-05-01

123

Accelerated Aging of Polymer Composite Bridge Materials  

SciTech Connect

Accelerated aging research on samples of composite material and candidate ultraviolet (UV) protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory (INEEL). Durability results and sensor data from tests with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards, and acceptance criteria for PMC bridges for use in the transportation infrastructure.

J. G. Rodriguez; L. G. Blackwood; L. L. Torres; N. M. Carlson; T. S. Yoder

1999-03-01

124

Mechanical Spectroscopy of Nanostructured Composite Materials  

NASA Astrophysics Data System (ADS)

The thermo-mechanical behavior of different nano-structured composite materials, which were processed within the SAPHIR European Integrated Project, has been characterized by mechanical spectroscopy. The obtained results show clearly that creep resistance of fine grain ceramics such as zirconia can be improved by carbon nano-tube (CNT) reinforcements. On the other hand the elastic modulus and the damping capacity of aluminum matrix composites were increased by SiC nano-particle additions. It has also been observed that CNT additions are responsible for a better thermal stability of polymer such as ABS (Acrylonitrile-Butadiene-Styrene) used in automotive industry.

Mari, Daniele; Schaller, Robert; Mazaheri, Mehdi

2011-07-01

125

Conductor-polymer composite electrode materials  

DOEpatents

A conductive composite material useful as an electrode, comprises a conductor and an organic polymer which is reversibly electrochemically dopable to change its electrical conductivity. Said polymer continuously surrounds the conductor in intimate electrical contact therewith and is prepared by electrochemical growth on said conductor or by reaction of its corresponding monomer(s) on said conductor which has been pre-impregnated or pre-coated with an activator for said polymerization. Amount of the conductor is sufficient to render the resultant composite electrically conductive even when the polymer is in an undoped insulating state.

Ginley, D.S.; Kurtz, S.R.; Smyrl, W.H.; Zeigler, J.M.

1984-06-13

126

Silane coupling agents used for natural fiber\\/polymer composites: A review  

Microsoft Academic Search

Natural fiber reinforced polymer composites (NFPCs) provide the customers with more alternatives in the material market due to their unique advantages. Poor fiber–matrix interfacial adhesion may, however, negatively affect the physical and mechanical properties of the resulting composites due to the surface incompatibility between hydrophilic natural fibers and non-polar polymers (thermoplastics and thermosets). A variety of silanes (mostly trialkoxysilanes) have

Yanjun Xie; Callum A. S. Hill; Zefang Xiao; Holger Militz; Carsten Mai

2010-01-01

127

Combustion products from advanced composite materials.  

PubMed

Recent advances in armament and materials applications are beginning to outpace the development of adequate safety characterizations. To avoid unnecessary and restrictive regulations implemented to protect individuals from potential toxic consequences resulting from exposure to combustion products of advanced composite materials (ACM); this laboratory has begun an investigation of combustion characteristics. In this preliminary investigation we have assessed the production of particulate matter and the production of organic compounds contained in both the combustion vapor phase or associated with the particulate matter. The results of these investigations have revealed that a substantial fraction of the particulates appear to be in the respirable range and that a high number of organic compounds and potential toxicants are associated with particulate matter. These findings are the first to describe the production of potentially toxic atmospheres from the combustion of advanced composite materials and indicate the usefulness of further investigations to quantify the risk of exposure to humans. These and forthcoming data will be useful in determining proper protective equipment and precautions required to protect human health during exposures to products from the combustion of advanced composite materials. PMID:9433657

Lipscomb, J C; Kuhlmann, K J; Cline, J M; Larcom, B J; Peterson, R D; Courson, D L

1997-11-01

128

Gold: compositional variations of naturally occurring alloys  

SciTech Connect

Naturally occurring gold is nearly always alloyed with silver, quantities of which may reach 40 or more percent, and frequently contains minor amounts of copper and mercury and traces of other metals. An extensive literatures search of analyses of gold alloys from world-wide localities, supplemented by several hundred additional electron microprobe analyses, yields the distribution pattern in terms of fineness (((Au)/(Au+Ag) wt %) x 1000). These data reveal few compositions in the range 0-500 fine and a maximum at approximately 920 fine. The near absence of compositions in the 0-500 fineness range and a few examples of coexisting silver and electrum (540 fine) suggest the existence of a miscibility gap at low temperatures. Copper contents generally increase with higher fineness; several natural examples reveal exsolution of cuprian gold and thus indicate another miscibility gap. Natural mercury contents are generally below 0.5 wt %, but placer gold grains commonly reveal surface contamination of mercury lost in streams by former recovery operations. Thin, sharply defined rims of very high fineness gold commonly have developed on placer gains in streams and soil zones.

Craig, J.R.; Rimstidt, J.D.

1985-01-01

129

Titanium composite materials for transportation applications  

NASA Astrophysics Data System (ADS)

Discontinuously reinforced titanium alloys containing in-situ formed TiB needles are emerging as candidate materials for advanced applications. This new family of titanium composites presents technical advantages, and it can be less expensive and easily amenable for net-shape manufacturing relative to titanium metal-matrix composites developed to date. The production of a master compound by a novel and cost-effective process called self-propagating high-temperature synthesis (SHS) has been studied. This master compound could be subsequently used in an investment casting process to obtain TiB-reinforced net-shape titanium-matrix composites. The SHS technique and its features were investigated in depth before a suitable master compound was defined and produced. Cast samples obtained from the addition of the master compound have been produced and the most important issues concerning the processing, microstructure, and mechanical properties are highlighted in this paper.

García de Cortazar, M.; Agote, I.; Silveira, E.; Egizabal, P.; Coleto, J.; Le Petitcorps, Y.

2008-11-01

130

Putting it Together: The Science and Technology of Composite Materials  

NSDL National Science Digital Library

Composite materials are light, strong, corrosion-resistant composites of two or more materials used commonly in manufacturing. This recent report is from the Australian Academy of Science with support from The Cooperative Research Centre for Advanced Composite Structures, Ltd. and the Commonwealth Department of Industry, Science and Resources. It gives information on the history, manufacturing techniques, and efficiency of composite materials. A glossary, reference list, and links to educational sites as well as other composite materials sites are also featured.

2000-01-01

131

Laboratory Blast Simulator for Composite Materials Characterization  

Microsoft Academic Search

\\u000a Blasts and explosives have raised serious concerns in recent years due to the fatal injury and catastrophic damage they have\\u000a caused in the combat zones and due to industrial accidents. Owing to their lightweight and complex damage process, fiber-reinforced\\u000a composite materials have been found to have higher energy absorption capability and to be able to generate less lethal debris\\u000a than

Guojing Li; Dahsin Liu

132

Nonlinear dielectric response of periodic composite materials  

Microsoft Academic Search

This paper addresses the rigorous treatment of the tunability effect (dc electric field driven variation of the permittivity)\\u000a in a high-contrast two dimensional periodic composite (a matrix of a large dielectric constant ferroelectric material with\\u000a linear dielectric inclusions). The theoretical analysis here shows that the trend established for the case of low linear dielectric\\u000a concentrations (that the dilution with a

A. Kolpakov; A. K. Tagantsev; L. Berlyand; A. Kanareykin

2007-01-01

133

Characterization of self-healing composite materials  

NASA Astrophysics Data System (ADS)

Damage occurs in almost every composite material in the form of microcracks that develop in the epoxy matrix that binds the fibers together. Researchers at the University of Illinois Urbana Champaign have recently developed a method to reverse the effects of, or heal, damage in the epoxy matrix. Their in-situ self-healing system uses embedded microcapsules and a catalyst that trigger a romp reaction in an effort to rebond the microcracks. Several models have been developed in an effort to predict how a composite laminate damages. One model in particular, the Continuous Damage Mechanics model, CDM that has been developed at West Virginia University uses material properties that are easily obtained from standard ASTM and ISO testing methods. The CDM model has been extended at West Virginia University to incorporate the effects of a self-healing system to develop a Continuous Damage and Healing Mechanics model, CDHM. In this work, a testing procedure to characterize the autonomic healing of polymer matrix composites is outlined, as well as the regenerative effects of the self-healing system. The capability of the CDHM model to predict the material properties of the self-healing system is also addressed. The CDHM model is validated with experimental results for various laminates fabricated out of E-glass/epoxy.

Ford, Kevin John

134

Chlorhexidine-releasing methacrylate dental composite materials.  

PubMed

Light curable antibacterial, dental composite restoration materials, consisting of 80 wt% of a strontium fluoroaluminosilicate glass dispersed in methacrylate monomers have been produced. The monomers contained 40-100 wt% of a 10 wt% chlorhexidine diacetate (CHXA) in hydroxyethylmethacrylate (HEMA) solution and 60-0 wt% of a 50/50 mix of urethane dimethacrylate (UDMA) and triethyleneglycol dimethacrylate (TEGDMA). On raising HEMA content, light cure polymerisation rates decreased. Conversely, water sorption induced swelling and rates of diffusion controlled CHXA release from the set materials increased. Experimental composites with 50 and 90 wt% of the CHXA in HEMA solution in the monomer were shown, within a constant depth film fermentor (CDFF), to have slower rates of biofilm growth on their surfaces between 1 and 7 days than the commercial dental composite Z250 or fluoride-releasing dental cements, Fuji II LC and Fuji IX. When an excavated bovine dentine cylinder re-filled with Z250 was placed for 10 weeks in the CDFF, both bacteria and polymers from the artificial saliva penetrated between the material and dentine. With the 50 wt% experimental HEMA/CHXA formulation, this bacterial microleakage was substantially reduced. Polymer leakage, however, still occurred. Both polymer and bacterial microleakage were prevented with a 90 wt% HEMA/CHXA restoration in the bovine dentine due to swelling compensation for polymerisation shrinkage in combination with antibacterial release. PMID:15955557

Leung, Danny; Spratt, David A; Pratten, Jonathan; Gulabivala, Kishor; Mordan, Nicola J; Young, Anne M

2005-12-01

135

Fibrous composite materials in dentistry and orthopaedics: review and applications  

Microsoft Academic Search

In this report, the usage of fibrous composite materials in dentistry and orthopaedics is reviewed. Furthermore, the authors introduced functionally graded composite dental post, aesthetic composite archwires and brackets, and braided carbon\\/PEEK composite compression bone plate. Functionally graded composite dental post has continuously varied stiffness and this function successfully solved stress concentration at the root. Aesthetic composite archwires made of

K Fujihara; K Teo; R Gopal; P. L Loh; V. K Ganesh; S Ramakrishna; K. W. C Foong; C. L Chew

2004-01-01

136

Material selection and grade optimization applied to aluminum matrix composites  

Microsoft Academic Search

A general model for the optimal use of materials based on structural optimization is derived. The competitiveness of materials\\u000a is assessed with merit parameters. The competition between materials (material selection optimization) and the role of the composition and microstructure for a given material (grade optimization) are analyzed. The model is applied to aluminum matrix composites. The influence of matrix material,

J. Eliasson; R. Sandstroem

1995-01-01

137

A Grammatical Approach for Customization of Laminated Composite Materials  

Microsoft Academic Search

The wide range of properties covered by the manufacturable fiber—matrix combinations of composite materials, along with their directional property characteristics, provides designers with material selection flexibility during designing composite material products. Meeting multiple property goals, however, complicates the design process as both the composite material selection and the component shape formation becomes intricate with the multiple loading conditions, which may

Soumitra Nandi; Zahed Siddique; M. Cengiz Altan

2011-01-01

138

Self-sensing structural composite materials  

NASA Astrophysics Data System (ADS)

Self-sensing was attained in lightweight structural composite materials, including those with polymer (epoxy), carbon and ceramic (Si3N 4) matrices. Either a volume of the composite or the interlaminar interface in the composite was used as the sensor. The use of the interlaminar interface as a sensor is a new approach, which was found to be effective in continuous carbon fiber epoxy-matrix composites for sensing temperature, moisture and damage. In case of temperature sensing, the interlaminar interface functioned as either a thermistor or a thermocouple junction. The thermocouple approach required the fibers in the contacting laminae to be dissimilar, whereas the thermistor approach did not. By using two crossply laminae, a two-dimensional array of sensors was attained and demonstrated to be effective for temperature distribution sensing. By measuring the contact electrical resistivity of the interlaminar interface during shear, the interlaminar shear process was monitored in real time. Study of the electrical conduction across the interlaminar interface led to the observation of apparent negative electrical resistance, which could be controlled by composite design. The use of a volume of a structural composite as the sensor and measurement of the volume electrical resistivity of the volume showed that continuous carbon fiber epoxy-matrix and carbon-matrix composites were effective for the self-sensing of strain and damage, whereas the SiC whisker Si3N 4-matrix composite was effective for the self-sensing of strain only. For the case of the epoxy-matrix composite, it was found that the four-probe method of resistance measurement was effective, whereas the two-probe method was not; it was also found that the though-thickness resistance was a sensitive indicator of matrix damage, while the longitudinal resistance was a less sensitive indicator. Polycrystalline beta-SiC fiber without a carbon core was found to be a piezoresistive strain sensor, but that with a carbon core was not. The consolidation of carbon fiber epoxy-matrix laminae during composite fabrication by lamination was monitored in real time by measurement of the through-thickness electrical resistivity. The consolidation was thus found to be hastened and to occur to a greater extent by increasing the pressure. The consequence of better consolidation remained after curing and subsequent cooling.

Wang, Shoukai

139

Characterization of cryogenic microcracking in carbon fiber\\/epoxy composite materials  

Microsoft Academic Search

Polymeric composite materials have been widely utilized to take advantage of their large specific strength and stiffness. These characteristics have made them attractive for use in aerospace applications as containment structures for cryogenic fluids. However, the anisotropic, heterogeneous, and viscoelastic nature of polymeric composite materials creates a unique set of challenges for the storage of cryogenic fluids. Mismatches in thermal

John Francis Timmerman

2003-01-01

140

POLYMER ENGINEERING: Research on composite materials at Liverpool University, Part 2: Energy absorbing composite materials  

Microsoft Academic Search

The ability of a composite material to absorb energy in its bulk rather than at the tip of a crack is very important when such materials are used in the automobile industry, for example to protect passengers from the consequences of high speed impact under crash conditions. Part 2 of this article describes research into the design and fabrication of

D. Hull

1983-01-01

141

Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites  

Microsoft Academic Search

Natural materials are renowned for their strength and toughness,,,,. Spider dragline silk has a breakage energy per unit weight two orders of magnitude greater than high tensile steel,, and is representative of many other strong natural fibres,,. The abalone shell, a composite of calcium carbonate plates sandwiched between organic material, is 3,000 times more fracture resistant than a single crystal

Bettye L. Smith; Tilman E. Schäffer; Mario Viani; James B. Thompson; Neil A. Frederick; Johannes Kindt; Angela Belcher; Galen D. Stucky; Daniel E. Morse; Paul K. Hansma

1999-01-01

142

Nondestructive evaluation of advanced ceramic composite materials  

SciTech Connect

Nondestructive evaluation techniques were developed to characterize performance degrading conditions in continuous fiber-reinforced silicon carbide/silicon carbide composites. Porosity, fiber-matrix interface bond strength, and physical damage were among the conditions studied. The material studied is formed by chemical vapor infiltration (CVI) of the matrix material into a preform of woven reinforcing fibers. Acoustic, ultrasonic, and vibration response techniques were studied. Porosity was investigated because of its inherent presence in the CVI process and of the resultant degradation of material strength. Correlations between porosity and ultrasonic attenuation and velocity were clearly demonstrated. The ability of ultrasonic transmission scanning techniques to map variations in porosity in a single sample was also demonstrated. The fiber-matrix interface bond was studied because of its importance in determining the fracture toughness of the material. Correlations between interface bonding and acoustic and ultrasonic properties were observed. These results are presented along with those obtained form acoustic and vibration response measurements on material samples subjected to mechanical impact damage. This is the final report on research sponsored by the US Department of Energy, Fossil Energy Advanced Research and Technology Development Materials Program. 10 refs., 24 figs., 2 tabs.

Lott, L.A.; Kunerth, D.C.; Walter, J.B.

1991-09-01

143

The Nature of Genetic Material Online Module  

NSDL National Science Digital Library

The Nature of Genetic Material, a new resource from Baylor College of MedicineâÂÂs comprehensive website, BioEd Online, is one module of a three-part, interactive Web-based course called Genes, Health and Society. [The course, which explores the rapidly evolving world of genetics and genomics, can be taken free of charge for professional or personal development. Each module stands alone. Educators can work through the modules in sequence or move freely among them.

Center for Educational Outreach and Center for Collaborative and Interactive Technologies * (Baylor College of Medicine;)

2010-05-27

144

Study on Nature of Material Flow and Transform Model of Material Flow Development State  

Microsoft Academic Search

In accordance with the material flow theory put forward by the authors, this paper divides the nature of material flow into inherent nature and non-inherent nature. The quantitative and qualitative changes of the non-inherent nature of material flow determine the development states of material flow, which mainly manifest three states, namely, traditional material flow, modern material flow and transform of

Hou Han-ping; Xu Shou-bo

2006-01-01

145

Synthesis of High Performance Thermoelectric Materials Directly from Natural Mineral  

NASA Astrophysics Data System (ADS)

We report high performance TE materials synthesized directly from natural mineral. Lattice dynamics and electronic band structure calculations suggest that the compound tetrahedrite (Cu12-xMxSb4S13), where M is transition metal such as Zn or Fe, will have low lattice thermal conductivity and good electronic transport properties. We have experimentally investigated the relationship between ZT and x content of different transition metals in synthetic tetrahedrites. We have found that the maximum of ZT value is not sensitive to the value of x but is related to valence band hole filling fraction; high ZT can be maintained over a large range of x. The compositions studied span the range of those of natural mineral tetrahedrite. To demonstrate that the natural mineral itself can be used as a source material, we synthesized samples by mixing natural mineral with synthetic Cu12Sb4S13 by balling milling and hot pressing. The resulting samples were single phase with hole filling fraction in the optimum range and displayed maximum ZT values of unity at 723K. This new synthesis method can directly use natural mineral to produce TE materials in large quantities with little effort.

Lu, Xu; Morelli, Donald; Xia, Yi; Zhou, Fei; Ozolins, Vidvuds; Chi, Hang; Zhou, Xiaoyuan; Uher, Ctirad

2013-03-01

146

Anatomy of a Natural Composite Material.  

National Technical Information Service (NTIS)

Sessile marine invertebrates deposit specialized protective coatings on extracellular structures such as holdfasts and shells. These coatings, once cured, are reknowned for their stability and durability (1-2 years). The precursors for these coatings are ...

J. H. Waite

1989-01-01

147

Calcium phosphate-based composites as injectable bone substitute materials.  

PubMed

A major weakness of current orthopedic implant materials, for instance sintered hydroxyapatite (HA), is that they exist as a hardened form, requiring the surgeon to fit the surgical site around an implant to the desired shape. This can cause an increase in bone loss, trauma to the surrounding tissue, and longer surgical time. A convenient alternative to harden bone filling materials are injectable bone substitutes (IBS). In this article, recent progress in the development and application of calcium phosphate (CP)-based composites use as IBS is reviewed. CP materials have been used widely for bone replacement because of their similarity to the mineral component of bone. The main limitation of bulk CP materials is their brittle nature and poor mechanical properties. There is significant effort to reinforce or improve the mechanical properties and injectability of calcium phosphate cement (CPC) and this review resumes different alternatives presented in this specialized literature. PMID:20336722

Low, Kah Ling; Tan, Soon Huat; Zein, Sharif Hussein Sharif; Roether, Judith A; Mouriño, Viviana; Boccaccini, Aldo R

2010-07-01

148

Damage and fracture mechanics of composite materials  

NASA Astrophysics Data System (ADS)

The design of structural systems in the aerospace industry has been characterized by a continuing search for strong, yet lightweight, materials to achieve maximum payload capability for minimum weight. In recent years, this search has led to a wide use of fiber reinforced composites, such as carbon, glass and kevelar based composites. Comparison of these new materials with the traditional ones (metals) according to the basic properties, such as density, elastic modulus and also long-time and short-time strength, shows their superiority over traditional materials, when weight is a major design factor, like in the aerospace industry. Most composite materials of interest to aerospace applications have been adequately characterized under static loading conditions. Related work to study their fracture behaviour has been limited. Since most failure mechanisms involve crack growth and/or delamination, design of such components requires knowledge and understanding of their fracture properties. This thesis includes an experimental and analytical investigation of fracture characteristics of composite materials. The post-peak response of notched specimens subjected to uniaxial cyclic loading is established to evaluate the fracture energy associated with progressive matrix damage and subsequent crack growth. A total of 75 uniaxial tension specimens were tested. The experimental work consisted of first testing several un-notched specimens with different thickness (number of layers) to determine the initial and secondary elastic modulus as well as the tensile strength. The investigation studied the effect of the various fracture parameters, including thickness, fiber orientation, and crack width ratio (a/w) on the behaviour of crack propagation, peak load, and post-peak response. The specimens used in this research were prepared using the vacuum bagging technique, with a chosen number of fiber glass cloth layers and fiber orientation. The experimental results provided information regarding the peak load, post-peak response, fracture energy and stress intensity factor of the notched composite materials specimen under repeated loading/unloading cyclicity. The load versus crack opening displacement as well as crack length, fracture toughness and fracture energy versus number of loading cycles are produced for different specimens. Based on the experimental results, concepts of fracture mechanics are applied to evaluate stiffness degradation, fracture toughness and fracture energy evolution associated with crack growth. In addition, a linear elastic fracture mechanics approach combined with continuum damage representation is used to predict the response of specimens (peak load and crack opening displacement). This effort has also generated a new crack band model for computational purposes. A new formula is derived to compute delamination and interlaminar buckling loads using the finite element method. By matching the analytical near crack tip displacement field with the finite element approximation, the crack-axial stress magnitude is established, and therefore an accurate assessment of the buckling load responsible for delamination of composites is accurately evaluated. A comprehensive derivation of the fracture inelastic zone size and shape in anisotropic solids is presented. An adaptation of Hill's failure criterion is used to derive the shape of the inelastic zone. The findings explain the "banded" shape of the damage zone observed during crack growth.

Abdussalam, Saleh Ramadan

149

Dental composites/glass ionomers: the materials.  

PubMed

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of water-soluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1292462

Bowen, R L; Marjenhoff, W A

1992-09-01

150

Orthotropic piezoelectric composite materials actuator and its preliminary application  

Microsoft Academic Search

In this paper, the laminated piezoelectric composite materials with orthotropic properties, the structures, performances of orthotropic piezoelectric actuation elements are studied. Orthotropic piezoelectric composite materials present remarkable differences in two primary directions perpendicular to each other. As actuation chips, the laminated orthotropic piezoelectric composite materials present opposite deformation tendencies in two primary directions, which conforms to the deformation law of

Ying Luo; Guoqi Zhao; Jianzu Gu; Zuting Liu

2002-01-01

151

FOREWORD: Focus on New Materials Mimicking Nature Focus on New Materials Mimicking Nature  

NASA Astrophysics Data System (ADS)

Living organisms have developed highly efficient structures and processes that consume little energy and produce minimal waste. These processes hold important information for nanotechnology and can lead to breakthroughs in the development of technologies with low environmental load. Therefore, interest in nature-inspired materials is increasing in many fields. In September 2008, the National Institute for Materials Science (NIMS) launched the Learning from Nature Cluster (LNC) with the objectives of probing the foundations of natural processes and pioneering a new materials science through a network of researchers working in different fields. The activities of the LNC during the past three years have resulted in this focus issue. It contains review articles on both the working mechanisms of natural materials and living organisms, and on the development of nature-inspired materials. It contains the following four topics: (1) geomaterials, (2) structural color by biomimetic approach, (3) biominerals and (4) adhesion and the interface of biological materials with the adherend. We are grateful to all the authors who contributed to this focus issue and hope it will become an important resource for the future development of this field.

Hosoda, Naoe; Fudouzi, Hiroshi

2011-12-01

152

Manufacturing of hard magnetic composite materials Nd-Fe-B  

Microsoft Academic Search

Purpose: This paper presents the material and technological solution which makes it possible obtaining of hard magnetic composite materials: nanocrystalline material - polymer. Design\\/methodology\\/approach: For fabrication of composite materials the Nd-Fe-B powder obtained by melt quenching technique was used and for matrix: epoxy resin (EP) or high density polyethylene (HDPE) (2.5 % wt.). Composite materials were compacted by the one-sided

M. Drak; B. Zi?bowicz; L. A. Dobrza?ski

153

PERSPECTIVE: Self-healing polymer composites: mimicking nature to enhance performance  

Microsoft Academic Search

Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies

R. S. Trask; H. R. Williams; I. P. Bond

2007-01-01

154

On the contribution of natural and restored wetlands to changes in the concentration and composition of dissolved organic material in the Sacramento-San Joaquin Delta and San Francisco Estuary.  

NASA Astrophysics Data System (ADS)

The amount and quality of wetland-derived dissolved organic material (DOM) entering delta and estuary environments remains poorly characterized even though DOM has two roles of societal significance: 1) it supports estuarine foodwebs, commonly habitat for endangered species, and 2) it presents problems when it occurs in drinking water supplies, forming carcinogenic byproducts on treatment. The Sacramento-San Joaquin Delta is a source of drinking water for over 20 million people and contributes 80% of the DOM entering the San Francisco Estuary, nearly doubling the concentration of DOM in the influent river water. The majority of the Delta is composed of below-sea level peat islands maintained in agricultural production by continuous pumping of DOM-rich drain water into Delta channels. Previous studies have shown that changes in the composition of the DOM in water that passes through the Delta are not consistent with addition of peat island drain water, and are more consistent with addition of wetland-derived material, suggesting that wetlands may contribute substantially to DOM export to the Estuary. Although wetlands currently contribute only 14% of the Delta, restoration is planned that would more than double this area, potentially altering DOM quality and content in the Delta and Estuary waters. Over the past several years we have examined the seasonal variation in the quality of DOM added by a variety of wetland types and island drains within the Delta and Estuary. In the current study, thirteen sites were each sampled five times. To date, we have analyzed the samples to determine the content of hydrophobic DOM, characterize the UV absorbance and fluorescence properties, and quantify the susceptibility to biodegradation both before and after photo-exposure. Samples were humic-rich, averaging over 75% hydrophobic content and varying from 74 to 86% with the variation in hydrophobic content between samples corresponding to changes in the optical properties. Samples typically were refractory with respect to biodegradation, with an average of 11% of the DOM susceptible to biodegradation prior to photoexposure, but the range was from 1% to 48%. Following photoexposure, samples were generally more refractory rather than more labile. Wetland DOM was found to react to form more drinking water disinfection byproducts than influent waters, but some wetland types appeared to contribute fewer precursors. Seasonal variation in biodegradation and chemical parameters was much greater than variation among wetland types, and the peak of biodegradeability was not related to the seasonal peak in DOM. This suggests addition of DOM through the Delta is controlled by changes in the nature of the source material rather than changes in efficiency or extent of remineralization.

Bergamaschi, B.; Stepanauskas, R.; Fram, M.; Hollibaugh, J.; Fujii, R.

2002-12-01

155

The Contribution of Natural and Restored Wetlands to Changes in the Concentration and Composition of Dissolved Organic Material in the Sacramento-San Joaquin Delta and San Francisco Estuary  

NASA Astrophysics Data System (ADS)

The quantity and quality of wetland-derived dissolved organic material (DOM) entering delta and estuary environments remains poorly characterized, even though DOM has two roles of societal significance: 1) it supports estuarine foodwebs, which commonly are a habitat for endangered species, and 2) it presents problems when it occurs in drinking water supplies, because it forms carcinogenic byproducts when treated. The Sacramento-San Joaquin Delta is a source of drinking water for more than 20 million people and contributes 80% of the DOM entering the San Francisco estuary, nearly doubling the concentration of DOM in the influent river water. The majority of the Delta is composed of below-sea-level peat islands that are maintained in agricultural production by continuous pumping of DOM-rich drain water into Delta channels. Previous studies indicate that changes in DOM composition in water passing through the Delta are not consistent with the addition of peat island drain water, and are more consistent with the addition of wetland-derived material. Therefore, wetlands may contribute substantially to DOM export to the estuary. Although wetlands currently constitute only 14% of the Delta, restoration is planned that would more than double this wetland area, potentially altering DOM quality and content in the Delta and estuary waters. During the past several years, the seasonal variation in the quality of DOM added by a variety of wetland types and island drains within the Delta and estuary has been examined. In this study, 13 sites were sampled 5 times. As of September 2002, the samples have been analyzed to determine the content of hydrophobic DOM, characterize the ultraviolet absorbance and fluorescence properties, and quantify the susceptibility to biodegradation before and after photoexposure. Samples were humic-rich, averaging more than 75% hydrophobic content and varying from 74 to 86%, with the variation in hydrophobic content between samples corresponding to changes in the optical properties. Samples typically were refractory with respect to biodegradation, having an average of 11% of the DOM being susceptible to biodegradation prior to photoexposure, but the range was from 1% to 48%. Following photoexposure, samples generally were more refractory rather than more labile. Wetland DOM reacted to form more drinking water disinfection byproducts than influent waters, but some wetland types seemed to contribute fewer precursors. Seasonal variation in biodegradation and chemical parameters was much greater than variation among wetland types, and the peak of biodegradability was not related to the seasonal peak in DOM. Therefore, the addition of DOM through the Delta is controlled by changes in the nature of the source material rather than changes in efficiency or extent of remineralization.

Bergamaschi, B. A.; Stepanauskas, R.; Fram, M.; Hollibaugh, J. T.; Fujii, R.

2002-12-01

156

Viscoelastic models for polymeric composite materials  

SciTech Connect

An improved model of the mechanical properties of the explosive contained in conventional munitions is needed to accurately simulate performance and accident scenarios in weapons storage facilities. A specific class of explosives can be idealized as a mixture of two components: energetic crystals randomly suspended in a polymeric matrix (binder). Strength characteristics of each component material are important in the macroscopic behavior of the composite (explosive). Of interest here is the determination of an appropriate constitutive law for a polyurethane binder material. A Taylor Cylinder impact test, and uniaxial stress tension and compression tests at various strain rates, have been performed on the polyurethane. Evident from time resolved Taylor Cylinder profiles, the material undergoes very large strains ({gt}100{percent}) and yet recovers its initial configuration. A viscoelastic constitutive law is proposed for the polyurethane and was implemented in the finite element, explicit, continuum mechanics code EPIC. The Taylor Cylinder impact experiment was simulated and the results compared with experiment. Modeling improvements are discussed. {copyright} {ital 1996 American Institute of Physics.}

Bardenhagen, S.G.; Harstad, E.N. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Foster, J.C. Jr. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)]|[Wright Laboratory, Armament Directorate, Eglin AFB, Florida 32542 (United States); Maudlin, P.J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1996-05-01

157

High velocity impact resistance of composite materials  

NASA Astrophysics Data System (ADS)

Composite materials are used in applications that require protection against high velocity impacts by fragment simulating projectiles. In this work, the ballistic performance of two commercially available materials against a fragments simulating projectile (FSP) is studied. The materials used were an aramid fiber with a phenolic matrix and a polyethylene fiber with a thermoplastic film. Impact tests have been carried out, with velocities ranging from 300 m/s to 1260m/s. The projectile used is a 1.1g NATO FSP. Impact velocity and exit velocity are measured, to determine the V{50} and the energy absorbed in cases where perforation occurs. Assessment of the impact damaged area is done using ultrasonic C-scan inspection. Types of damage and damage mechanisms have been identified. Several mechanical tests have been carried out to determine the mechanical properties, at different strain rates. Future work in numerical simulation of impact will be done using commercial code AutodyntinycircledR ftom Century Dynamics.

Justo, Jo; Marquer, A. T.

2003-09-01

158

Aluminium composite materials for multichip modules  

SciTech Connect

This paper reports that, as a result of continued advances in microelectronics, packaging technologies have become ital to the success of advanced designs. Progress in this field has been driven by advances in active device technologies that have resulted in significant miniaturization, increased functional density, and higher operating frequencies. These developments have produced ever-increasing power densities requiring improve thermal management schemes. In particular, multichip modules (MCMs) present challenges because they contain several devices in close proximity. The alternatives to improve cooling schemes-higher junction temperatures and decreased reliability-are clearly unacceptable. Requirements for improved cooling are complicated further in avionics systems by the need to minimize system weight and in automotive systems by the need to provide protection from a more hostile environment while maintaining low cost. These needs are driving materials developments along a number of fonts, as reviewed in Carl Zweben's article in this issue. Unfortunately, no current-generation material can meet all of these challenges. The use of aluminum or copper results in unacceptable expansion stress on silicon- or gallium arsenide-based devices. Kovar is costly to manufacture in complex configurations and ins inherently poor in thermal conductivity. The Cu/W and Cu/Mo blends, either in the form of metallurgical or macroscopic composites, offer good thermal conductivity but are inherently heavy and are manufactured from expensive raw materials.

Premkumar, M.K.; Hunt, W.H. Jr.; Sawtell, R.R. (Innometalx Group, Alcoa Center, PA (US))

1992-07-01

159

Effective thermal conduction in composite materials  

NASA Astrophysics Data System (ADS)

The problem of determining the bounds and/or estimating the effective thermal conductivity ( ? eff) of a composite (multiphase) system given the volume fractions and the conductivities of the components has been investigated. A comparison between the measured data and the results predicted by theoretical models has been made for seven heterogeneous samples. The tested models include those of the effective medium theory (EMT), Hashin and Shtrikman (HS) bounds, and Wiener bounds. These models can be used to characterize macroscopic homogeneous and isotropic multiphase composite materials either by determining the bounds for the effective thermal conductivity and/or by estimating the overall conductivity of the random mixture. It turns out that the most suitable one of these models to estimate ? eff is the EMT model. This model is a mathematical model based on the homogeneity condition which satisfies the existence of a statistically homogeneous medium that encloses inclusions of different phases. Numerical values of thermal conductivity for the samples that satisfy the homogeneity condition imposed by the effective medium theory are in best agreement with the experimentally measured ones.

Suleiman, Bashir M.

2010-04-01

160

Lightweight Impact-Resistant Composite Materials: Lessons from Mantis Shrimp  

NASA Astrophysics Data System (ADS)

Nature has evolved efficient strategies to synthesize complex mineralized structures that exhibit exceptional damage tolerance. One such example is found in the hyper-mineralized hammer-like dactyl clubs of the stomatopods, a group of highly aggressive marine crustaceans. The dactyl clubs from one such species, Odontodactylus Scyllarus, exhibit an impressive set of characteristics adapted for surviving high velocity impacts with the heavily mineralized prey species on which they feed. Consisting of a multi-phase composite of oriented crystalline hydroxyapatite and amorphous calcium phosphate and carbonate, in conjunction with a highly expanded helicoidal organization of the fibrillar chitinous organic matrix, these structures display several effective lines of defense against catastrophic failure during repetitive high energy loading events. The study of this organism and its relatives has lead to design cues, which were incorporated into prototype composite materials designed for applications in aviation, body armor, and entertainment.

Milliron, Garrett Wayne

161

DBR PSi\\/PMMA composite materials for smart patch application  

Microsoft Academic Search

New nanostructured composite materials based on porous silicon (PSi) have been developed as a smart patch type for drug delivery applications. Distributed Bragg reflector (DBR) PSi films and caffeine-impregnated polymethyl methacrylate (PMMA) are used to produce flexible and stable composite materials in which the porous silicon matrix is covered with polymer. DBR PSi films and the composite films display a

Youngdae Koh; Seunghyun Jang; Jihoon Kim; Sungsoo Kim; Young Chun Ko; Sungdong Cho; Honglae Sohn

2008-01-01

162

Review on advanced composite materials boring mechanism and tools  

Microsoft Academic Search

With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre\\/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher

Runping Shi; Chengyong Wang

2010-01-01

163

Mechanics of composite materials - A unified micromechanical approach  

Microsoft Academic Search

This book presents a unified theory for the prediction of the overall behavior of composite materials. After discussing the fundamentals of the mechanics of composites, several basic composite models are described, together with the micromechanical method of cells for the analysis of elastic composites with aligned continuous or short fibers. The cell method is used to predict the strength and

Jacob Aboudi

1991-01-01

164

Method for preparing polyolefin composites containing a phase change material  

DOEpatents

A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein. The composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

Salyer, Ival O. (Dayton, OH)

1990-01-01

165

Electronic materials high- Tc superconductivity polymers and composites structural materials surface science and catalysts industry participation  

SciTech Connect

The fifth year of the Center for Advanced Materials was marked primarily by the significant scientific accomplishments of the research programs. The Electronics Materials program continued its work on the growth and characterization of gallium arsenide crystals, and the development of theories to understand the nature and distribution of defects in the crystals. The High-{Tc} Superconductivity Program continued to make significant contributions to the field in theoretical and experimental work on both bulk materials and thin films and devices. The Ceramic Processing group developed a new technique for cladding YBCO superconductors for high current applications in work with the Electric Power Research Institute. The Polymers and Composites program published a number of important studies involving atomistic simulations of polymer surfaces with excellent correlations to experimental results. The new Enzymatic Synthesis of Materials project produced its first fluorinated polymers and successfully began engineering enzymes designed for materials synthesis. The Structural Materials Program continued work on novel alloys, development of processing methods for advanced ceramics, and characterization of mechanical properties of these materials, including the newly-documented characterization of cyclic fatigue-crack propagation behavior in toughened ceramics. Finally, the Surface Science and Catalysis program made significant contributions to the understanding of microporous catalysts and the nature of surface structures and interface compounds.

Not Available

1988-01-01

166

Nature of branching in disordered materials  

NASA Astrophysics Data System (ADS)

The phenomenon of structural branching is ubiquitous in a wide array of materials such as polymers, ceramic aggregates, networks and gels. These materials with structural branching are a unique class of disordered materials and often display complex architectures. Branching has a strong influence over the structure-property relationships of these materials. Despite the generic importance across a wide spectrum of materials, our physical understanding of the scientific nature of branching and the analytic description and quantification of branching is at an early stage, though many decades of effort have been made. For polymers, branching is conventionally characterized by hydrodynamic radius (size exclusion chromatography, SEC, rheology) or by counting branch sites (nuclear magnetic resonance spectroscopy, NMR). SEC and rheology are, at best, qualitative; and quantitative characterization techniques like NMR and transmission electron microscopy (TEM) (for ceramic nanoparticulate aggregates) have limitations in providing routine quantification. Effective structure characterization, though an important step in understanding these materials, remains elusive. For ceramic aggregates, theoretical work has dominated and only a few publications on analytic studies exist to support theory. A new generic scaling model is proposed in Chapter I, which encompasses the critical structural features associated with these complex architectures. The central theme of this work is the application of this model to describe a variety of disordered structures like aggregated nano-particulates, long chain branched polymers like polyethylene, hyperbranched polymers, multi-arm star polymers, and cyclic macromolecules. The application of the proposed model to these materials results in a number of fundamental structural parameters, like the mass-fractal dimension, df, the minimum path dimension, dmin, connectivity dimension, c, and the mole fraction branch content, ?br. These dimensions reflect different features of the global structure, and it is categorically shown that this dimensional analysis results in effective structure characterization of these materials. Small-angle scattering of x-rays and neutrons can be used to quantify branch content and characterize the structure, through application of concepts native to fractal geometry. The application of the scaling model to nano-particulate aggregates yields quantitative information regarding the structure of these materials. In-situ small and ultra small angle x-ray scattering data collected on fumed silica and soot particles is presented in Chapter II. These measurements were performed at Advanced Photon Source, Argonne National Laboratory, UNICAT beam-line and the European Synchrotron Radiation Facility, Grenoble, France, ID2 beam-line. The dimensional analysis is successful in not only giving an average snap-shot of the nano-particulate aggregates, but also yields information regarding the growth processes involved in the complex pyrolysis technique of synthesizing these materials. In case of macromolecular systems, the minimum path dimension, dmin, is shown to reflect the thermodynamics of the system. This is categorically established in Chapter III on hyperbranched polymers, where the scaling model accurately predicts the good-solvent to theta-condition transition in these highly branched polymers with increasing molar mass. The scaling model is applied to the long standing problem of quantifying long chain branching in polyethylene in Chapter IV. Small angle neutron scattering data on dilute solutions of polyethylene were obtained at the Intense Pulsed Neutron Source (SAND beam-line); NIST center for Neutron Scattering (NG3 beam-line); and Los Alamos Neutron Scattering Center (LQD beam-line). This work, for the first time in literature, reports the length of a long chain branch in polyethylene in terms of the average molar mass of the branches, and the average number of carbon atoms in the long chain branch. Cyclic polymers are examined in the Chapter V. The scaling model presents a new

Kulkarni, Amit S.

167

Compression under conditions of the plane-strain state of composite powdered materials  

SciTech Connect

The deviator part of the stress tensor has a key effect on the compaction of a highly-porous powdered material. The composition of the powder mixture promotes strengthening processes in the plastic phase. The nature of the macroscopic behavior of the composite powdered mixture is affected substantially by the reinforcement of contacts between particles.

Leshchinskii, V.M.; Blokhin, A.G.; Ermolaeva, I.E. [Eastern Ukrainian State Univ., Lugansk (Ukraine)

1995-03-01

168

Nanostructured Shape Memory Alloys: Adaptive Composite Materials and Components.  

National Technical Information Service (NTIS)

Methods for fabricating adaptive composite materials and components using shape memory alloy (SMA) constituents were investigated using a variety of fabrication techniques, including mechanical rolling methods. Both SMA- polymer and SMA-metal composites w...

A. B. Ellis J. H. Perepezko W. C. Crone

2007-01-01

169

Power Composites: Structural Materials that Generate and Store Electrical Energy.  

National Technical Information Service (NTIS)

We describe progress in the development of a synthetic multifunctional material: namely a fiber composite with both power and structural function. The structural composite contains batteries encased in piezoelectric tubes. When the structure vibrates the ...

D. A. Shockey S. C. Ventura S. C. Narang J. W. Simons B. C. Bourne

2005-01-01

170

Soviet Developments in Composite Materials, January - June 1975.  

National Technical Information Service (NTIS)

Selected Soviet publications on composite materials over a period of 6 months (January to June 1975) are abstracted in this report. The publications cover both experimental and theoretical research on carbon fiber-reinforced plastic composites and carbon ...

J. Kourilo

1976-01-01

171

Developing polymer composite materials: carbon nanotubes or graphene?  

PubMed

The formation of composite materials represents an efficient route to improve the performances of polymers and expand their application scopes. Due to the unique structure and remarkable mechanical, electrical, thermal, optical and catalytic properties, carbon nanotube and graphene have been mostly studied as a second phase to produce high performance polymer composites. Although carbon nanotube and graphene share some advantages in both structure and property, they are also different in many aspects including synthesis of composite material, control in composite structure and interaction with polymer molecule. The resulting composite materials are distinguished in property to meet different applications. This review article mainly describes the preparation, structure, property and application of the two families of composite materials with an emphasis on the difference between them. Some general and effective strategies are summarized for the development of polymer composite materials based on carbon nanotube and graphene. PMID:23813859

Sun, Xuemei; Sun, Hao; Li, Houpu; Peng, Huisheng

2013-07-01

172

Microrobotics using composite materials: the micromechanical flying insect thorax  

Microsoft Academic Search

The use of high performance composite materials provides a substantial performance improvement for microrobotics. Such materials have great beneflts over common MEMs materials such as better frac- ture toughness and fatigue properties than semicon- ductors, and higher stifiness to weight ratios than most metals. Composite structures yield remarkable improvements in microrobotic links and joints, as well as greater performance actuators

Robert J. Wood; Srinath Avadhanula; M. Menon; Ronald S. Fearing

2003-01-01

173

Using of Composite Material in Wind Turbine Blades  

Microsoft Academic Search

The turbines manufactured from the mid 1980s until the late 1990s were mainly constructed using standard components. After that period, special components started being designed and manufactured for turbine use only. One of the best solutions is using composite materials in wind turbine. Most composites are made up of just two materials. One material (the matrix or binder) binds together

Bulent Eker; Aysegul Akdogan; Ali Vardar

2006-01-01

174

Nickel composite magnetostrictive material research for ultrasonic transducer  

Microsoft Academic Search

The immediate objective was to manufacture and test a composite transducer material of the compound SmFe2 in a nickel matrix fabricated by a powder metallurgy technique. The long term objective was the effective utilization of a 'giant' magnetostrictive REFe2 material in a ductile and corrosion resistant composite for use as a transducer core material.

D. T. Peters; E. L. Huston

1977-01-01

175

Natural Shock Sintering of Unconsolidated Planetary Materials  

NASA Astrophysics Data System (ADS)

On Earth, the transformation of unconsolidated sediment (e.g., sand) to rock (sandstone) occurs via the process of lithification. Lithification typically occurs via burial within the upper crust at less than 150 degrees celsius, at depths of less than 5 km in the presence of liquid H2O. Liquid H2O is often important in the process of lithification because it is the transporting medium for dissolved and suspended ions and mineral species, which eventually precipitate as a cement that binds the unconsolidated grains. Lithification also applies to sedimentary deposits formed by precipitation of minerals from aqueous solutions at surface, or near- surface, conditions (e.g., to generate sulfate or carbonate-rich evaporites). However, for many planetary bodies in our solar system, there are no large sources of liquid H2O to facilitate this type of lithification process. Despite the absence of water on such bodies, the development of consolidated fragmental material is commonplace and it probably dominates the surface materials of Mercury, the Moon, Mars and many asteroids. This material, typically in the form of breccias, is a relatively coherent rock, yet the nature of the "glue" that binds the fragments is not well understood. Clearly, other processes are responsible for the lithification that we take for granted in many of the sedimentary rocks developed on our wet planet. This work explores these processes. For certain planetary bodies unconsolidated material may be bound by ices, such that it possesses rock-like properties in terms in strength and behaviour. In the absence of H2O, unconsolidated semi-molten material can be lithified by welding and compaction (e.g., certain pyroclastic discharges that fall and accumulate to form ignimbrites). This requires the production of hot volcanogenic or impact ejecta. In this work we explore the nature of the binding medium in different types of lunar breccia collected during the Apollo15, 16 and 17 missions, in meteorites of the howardite, eucrite and diogenite (HED) class and in laboratory shocked lunar regolith samples. Analytical scanning electron microscopy (SEM) and field emission SEM are used to explore the microstructures. The samples are grouped as: (1) being primarily derived from unconsolidated lunar regolith; (2) impact melt rocks, and (3) samples that were primarily derived from solid rock that were impact brecciated. There is significant overlap between these groups. All may exhibit relatively high degrees of porosity, especially regoliths and breccias. Features that affect the cohesiveness and coherence of the rock product are given particular attention. For this study, bridges are necks between grains, intergranular melts are melts that have developed between grains, fused grains are grains that are joined at a contact interfaces with no visible neck, and annealed fractures are fractures that have been partially or totally closed by either diffusion across the fracture or melting either side of the fracture. The various mechanisms of lithification are explored and discussed. Localized heating appears to be the dominant welding process. Heat generation can be attributed to (a) energy release due to frictional movement between grains during bulk (impact-generated) compression and (b) shock wave energy dissipation, especially between grains with high impedance contrasts and at grain (and other microstructural) boundaries. For unconsolidated materials, the resultant microtextures are akin to products of the industrial shock sintering of powders, and analogies are drawn between these two processes.

Spray, J. G.

2006-12-01

176

High strain-rate behavior of natural fiber-reinforced polymer composites  

Microsoft Academic Search

The high strain-rate constitutive behavior of polymer composites with various natural fibers is studied. Hemp, hemp\\/glass hybrid, cellulose, and wheat straw-reinforced polymeric composites have been manufactured, and a split-Hopkinson pressure bar apparatus has been designed to measure the dynamic stress–strain response of the materials. Using the apparatus, compressive stress–strain curves have been obtained that reveal the materials’ constitutive characteristics at

Wonsuk Kim; Alan Argento; Ellen Lee; Cynthia Flanigan; Daniel Houston; Angela Harris; Deborah F Mielewski

2012-01-01

177

Composite materials for extremely large mirrors and optical structures  

NASA Astrophysics Data System (ADS)

Building on our successful production of a world-class dimensionally stable composite optical bench structure for the SOLAR-B space telescope, Mitsubishi Electric is continuing to develop high performance lightweight composites for optical structures including mirrors. A key feature of composite materials is the ability to design the material to optimally meet the application requirements. Thus, various materials with individual characteristics are under development, each providing significant improvement over the state of the art.

Ozaki, Tsuyoshi; Hahn, Steven

2004-07-01

178

Kinetic determination of rare elements of the platinum group in natural materials  

SciTech Connect

Methods for kinetic determination of osmium, ruthenium, and iridium have been developed. The preparation of samples of different composition, namely, sulfide, oxide, silicate, biogeochemical, and natural waters, is described. Schemes are given for analysis of natural materials for concentration of rare elements of the platinum group.

Romanovskaya, L.E.; Khomutova, E.G.; Rysev, A.P. [M.V. Lomonosov Moscow State Academy of Fine Chemical Engineering (Russian Federation)

1995-02-01

179

Orthotic Devices Using Lightweight Composite Materials.  

National Technical Information Service (NTIS)

Potential applications of high strength, lightweight composite technology in the orthotic field were studied. Several devices were designed and fabricated using graphite-epoxy composite technology. Devices included shoe plates, assistive walker devices, a...

E. Harrison

1983-01-01

180

Discrimination of naturally occurring radioactive material in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is used in many applications for the detection of gamma rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The

J. H. Ely; R. T. Kouzes; B. D. Geelhood; J. E. Schweppe; R. A. Warner

2004-01-01

181

Discrimination of naturally occurring radioactive material in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is used in many applications for the detection of gamma rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The

James H. Ely; Richard T. Kouzes; Bruce D. Geelhood; John E. Schweppe; Ray A. Warner

2003-01-01

182

Maleated coupling agents for natural fibre composites  

Microsoft Academic Search

Maleated coupling agents are widely used to strengthen composites containing fillers and fibre reinforcements. The established role of MaPOs results from two main factors, economical manufacturing and the efficient interaction of maleic anhydride with the functional surface of fibre reinforcements. Peak performance was demonstrated in agrofibre polypropylene composites by selecting a maleated coupler that has the appropriate balance of molecular

T. J. Keener; R. K. Stuart; T. K. Brown

2004-01-01

183

Short natural-fibre reinforced polyethylene and natural rubber composites: Effect of silane coupling agents and fibres loading  

Microsoft Academic Search

Composites materials based on cellulose fibres (raw or chemically modified) as reinforcing elements and thermoplastic matrices were prepared and characterized, in terms of mechanical performances, thermal properties and water absorbance behaviour. Four different cellulose fibres with different average lengths were used, namely avicel, technical, alfa pulps and pine fibres. Two thermoplastic polymers, i.e. low density polyethylene and natural rubber, were

M. Abdelmouleh; S. Boufi; M. N. Belgacem; A. Dufresne

2007-01-01

184

A Review on the Natural Fiber-Reinforced Polymer Composites for the Development of Roselle Fiber-Reinforced Polyester Composite  

Microsoft Academic Search

In recent years, the interest of scientists and engineers has turned over on utilizing all plant fibers as effectively and economically as possible to produce good quality fiber-reinforced polymer composites for structural, building, and other needs. It is because of the high availability of the natural resources in this green world. This has led to the development of alternative materials

M. Thiruchitrambalam; A. Athijayamani; S. Sathiyamurthy; A. Syed Abu Thaheer

2010-01-01

185

Acoustical and fire-retardant properties of jute composite materials  

Microsoft Academic Search

This research aims to study the acoustical and flammability properties of biodegradable and easily disposable natural fibre jute and its composite for noise reduction in house hold appliances, automotive and architectural applications. Acoustical properties of jute fibre and felt (natural rubber latex jute composite) were measured in terms of normal specific sound absorption coefficient and sound transmission loss whereas fire

S. Fatima; A. R. Mohanty

2011-01-01

186

Formation and ultrasonic removal of fouling particle structures in a natural porous material  

Microsoft Academic Search

Formation and ultrasonic removal of fouling particle structures in a porous material (caused by the flow of a liquid with small through the material) was studied with natural sandstone. Fouling particles were generated inside the sandstone by changing the composition of the liquid from a 2% KCl brine solution to fresh water. The influence of liquid velocity, particle concentration and

Pietro Poesio; Gijs Ooms

2004-01-01

187

Vibration Characteristics of Aluminum Plates Reinforced with Boron-Epoxy Composite Material  

Microsoft Academic Search

Vibration characteristics of aluminum plates reinforced with boron epoxy composite material were investigated experimentally and analyt ically. Variations in the natural frequencies, mode shapes, and damping with filament angle were studied. Vibration characteristics of the re inforced plates were also compared with all-aluminum plates.Results of this study demonstrate the merit of using directional com posite materials in design for controlling

Robert R. Clary; Paul A. Cooper

1973-01-01

188

Nanostructured Composite Materials for High Temperature Thermoelectric Energy Conversion.  

National Technical Information Service (NTIS)

The goals of this project were to synthesize, characterize and model bulk nanostructured composite materials for thermoelectric energy conversion applications. The objective was to produce materials which demonstrate an increase in intrinsic thermoelectri...

C. J. O'Connor

2012-01-01

189

Preparation of Composite Materials in Space. Volume 2 Technical Report.  

National Technical Information Service (NTIS)

A study to define promising materials, significant processing criteria, and the related processing techniques and apparatus for the preparation of composite materials in space was conducted. The study also established a program for zero gravity experiment...

W. H. Steurer S. Kaye

1973-01-01

190

HDPE Wood-Plastic Composite Material Model Subject to Damage.  

National Technical Information Service (NTIS)

The information presented in this thesis is part of an ongoing research project being performed at Washington State University to develop wood-plastic composite materials for waterfront structures. Material development has been finished and relevant infor...

G. Lu

2002-01-01

191

Material, process, and product design of thermoplastic composite materials  

NASA Astrophysics Data System (ADS)

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength were tested experimentally and evaluated analytically. The thermoplastic adhesive interface was investigated with environmental scanning electron microscopy. The wood/composite structural design was optimized and evaluated using a Graphic Method. In the second application, we evaluated use of thermoplastic composites for explosion containment in an arrester. PP/glass yarn was fabricated in a sleeve form and wrapped around the arrester. After consolidation, the flexible composite sleeve forms a solid composite shell. The composite shell acts as a protection layer in a surge test to contain the fragments of the arrester. The manufacturing process for forming the composite shell was designed. Woven, knitted, and braided textile composite shells made of commingled PP/glass yarn were tested and evaluated. Mechanical performance of the woven, knitted, and braided composite shells was examined analytically. The theoretical predictions were used to verify the experimental results.

Dai, Heming

192

Composite tribological materials. (Latest citations from Fluidex). Published Search  

SciTech Connect

The bibliography contains citations concerning the properties, behavior, and uses of composite tribological materials in and on various objects, devices, and equipment. The citations examine friction and wear characteristics, mechanisms, and the performance of these materials and the objects to which they are applied. Composite tribological materials are used, for example, in bearings, gears, and piston rings. Included are self lubricating materials. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1998-02-01

193

Environmental effects on composite materials. Volume 3  

SciTech Connect

The present collection of papers, each of which has previously been abstracted in International Aerospace Abstracts, discusses the accelerated environmental testing of composites, moisture solubility and diffusion in epoxy and epoxy-glass composites, the influence of internal and external factors affecting moisture absorption in polymer composites, long-tern moisture absorption in graphite/epoxy angle-ply laminates, the effect of UV light on Kevlar 49-reinforced composites, and temperature and moisture induced deformation in composite sandwich panels. Also discussed are the orthotropic thermoelastic problem of uniform heat flow distributed by a central crack, the effect of microcracks on composite laminate thermal expansion, the stress analysis of wooden structures exposed to elevated temperatures, and the deflection of plastic beams at elevated temperatures.

Springer, G.S.

1988-01-01

194

Environmental effects on composite materials. Volume 3  

Microsoft Academic Search

The present collection of papers, each of which has previously been abstracted in International Aerospace Abstracts, discusses the accelerated environmental testing of composites, moisture solubility and diffusion in epoxy and epoxy-glass composites, the influence of internal and external factors affecting moisture absorption in polymer composites, long-tern moisture absorption in graphite\\/epoxy angle-ply laminates, the effect of UV light on Kevlar 49-reinforced

1988-01-01

195

Materials characterisation and crash modelling of composite-aluminium honeycomb sandwich material  

Microsoft Academic Search

Composite sandwich materials are extensively used in aerospace, motorsport and other applications that require low-weight, high-stiffness materials with high strength and energy absorption. In Formula 1 vehicles, composite-aluminium sandwich materials are used for the energy absorbing structures and the protective cell for the driver. Generally, the loading and failure mechanisms in sandwich composite materials are well understood. However, their behaviour

A. K. Pickett; A. J. Lamb; F. Chaudoye

2009-01-01

196

Methodology for Evaluating Manufacturability of Composite Materials  

NASA Astrophysics Data System (ADS)

It is widely acknowledged that decisions made in the early design stages have a greater influence on the final product than those made in the later stages. In a conventional design process, composite products are designed without sufficient consideration being given to limitations of composite manufacturing process. Quite often some of composite designs cannot be produced with special performance requirement or cannot be produced at a reasonable cost. To resolve this drawback and achieve the competitive designs for composite product, an integrated knowledge framework that supports the quantitative manufacturability evaluation of composite design proposals was introduced. The essential concept of the composite manufacturability was defined through an in-depth analysis of composite manufacturing process. The evaluation flow was acquired according to the hierarchical indices. A stage-based quality assessment model for the composite multistage process was mainly studies. It relies on the consideration that the final quality of a composite product is mainly determined by some critical stages during a production cycle. Finally, the method is illustrated through a case focusing on the quality issue of void formation in autoclave process.

Cong, Jingjie; Zhang, Boming

2012-06-01

197

Microstructural design of composite materials for crashworthy structural applications  

Microsoft Academic Search

Traditionally, metals are used for crashworthy structural applications, mainly due to their plastic deformation characteristics that enable them to absorb impact energy in a controlled manner. Unlike the metals, polymer composite materials display little plastic deformation characteristics. The use of polymer composites for crashworthy structural applications is a major challenge for the composite community. Current research work clearly suggests that

S Ramakrishna

1997-01-01

198

Characterization and prediction of abrasive wear of powder composite materials  

Microsoft Academic Search

Composite materials produced by powder metallurgy provide a solution in many engineering applications where materials with high abrasion and erosion resistance are required. The actual wear behaviour of the material is associated with many external factors (particle size, velocity, angularity, etc.) and intrinsic material properties (hardness, toughness, Young modulus, etc.). Hardness and toughness properties of such tribomaterials are highly dependent

R. Veinthal; P. Kulu; J. Pirso; H. Käerdi

2009-01-01

199

CFRP\\/titanium hybrid material for improving composite bolted joints  

Microsoft Academic Search

The structural joining remains an essential challenge for the development of composite aerospace structures: every structural interconnection means a disturbance of an optimized structure resulting in an increase in overall structural weight. The lightweight potential of advanced, high-performance fiber composite materials is affected more strongly by mechanical fastening techniques than by conventional metallic materials due to the low shear and

B. Kolesnikov; L. Herbeck; A. Fink

2008-01-01

200

Biomedical applications of polymer-composite materials: a review  

Microsoft Academic Search

An overview of various biomedical applications of polymer-composite materials reported in the literature over the last 30 years is presented in this paper. For the benefit of the readers, general information regarding structure and function of tissues, types and purpose of implants\\/medical devices, and various other materials used, are also briefly presented. Different types of polymer composite that are already

S. Ramakrishna; J. Mayer; E. Wintermantel; Kam W Leong

2001-01-01

201

Thermophysical Analysis of High Modulus Composite Materials for Space Vehicles  

Microsoft Academic Search

High modulus composite materials are used extensively in aerospace vehicles mainly for the purpose of increasing strength and reducing weight. However, thermal properties have become essential design information with the use of composite materials in the thermal design of spacecraft and spacecraft electronics packages. This is because the localized heat from closely packed devices can lead to functional failure of

Ho-Sung Lee

2009-01-01

202

Development of methods for synthesis of surface-modified fluoropolymer-containing composite materials  

Microsoft Academic Search

The results of studies into development of methods for synthesizing new modified fluoropolymer-containing composite materials\\u000a were summarized. The issues covered include: new modes and initiation methods of graft polymerization of fluoromonomers onto\\u000a the surface of items of various nature and dispersity without homopolymer formation; nature of the surface active centers\\u000a of the modified material and how it affects the kinetics

M. R. Muidinov

2009-01-01

203

21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.  

Code of Federal Regulations, 2010 CFR

... Polytetrafluoroethylene with carbon fibers composite implant material... Polytetrafluoroethylene with carbon fibers composite implant material...A polytetrafluoroethylene with carbon fibers composite implant...

2009-04-01

204

21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.  

Code of Federal Regulations, 2010 CFR

... Polytetrafluoroethylene with carbon fibers composite implant material... Polytetrafluoroethylene with carbon fibers composite implant material...A polytetrafluoroethylene with carbon fibers composite implant...

2010-04-01

205

Wear behaviour of aluminium matrix composite materials  

Microsoft Academic Search

Wear behaviour of aluminium matrix composites is characterized by the dry spindle wear test under various conditions (volume fractions of reinforcements, sliding distances and speeds). Wear resistance of composites is improved due to the presence of reinforcements, but no noticeable improvements are observed in the wear resistance with more than 20% addition of reinforcements. To analyse wear mechanisms, wear surfaces

C. S. Lee; Y. H. Kim; K. S. Han; T. Lim

1992-01-01

206

Flexible hydrogel-based functional composite materials  

DOEpatents

A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

2013-10-08

207

Automobile leaf springs from composite materials  

Microsoft Academic Search

The automobile industry has shown increased interest in the replacement of steel springs with fiberglass reinforced composite leaf springs. Therefore, the aim of this paper is to present a general study on the analysis, design and fabrication of composite springs. From this viewpoint, the suspension spring of a compact car, “a jeep” was selected as a prototype.A single leaf, variable

H. A. Al-Qureshi

2001-01-01

208

Tungsten filament as a reinforcing material for heat resistant composite materials  

Microsoft Academic Search

Translated from Metalloved. Term. Obrab. Metal.; 15: No. 7, 45-46(Jul ; 1973). Composite materials incorporating W wires in steel matrix were ; investigated. Data on wire and matrix composition are tabulated along with data ; on composite short-term strength. It is noted that the reinforcing filaments are ; weakened by recrystallization during prolonged use of the composite. (JRD);

F. P. Banas; A. B. Natapova; A. A. Shegai; Yu. V. Sukhanov

1973-01-01

209

New possibilities of composite materials application—Materials of specific magnetic properties  

Microsoft Academic Search

This paper presents the material and technological solution which makes it possible obtaining of soft and hard magnetic composite materials: nanocrystalline material–polymer. For fabrication of composite materials the following powders were used: soft magnetic material (Fe73.5Cu1Nb3Si13.5B9) and hard magnetic material (Nd14.8Fe76Co4.95B4.25). Polymer was used as the matrix (2.5wt.%). Advanced composite materials were compacted by the one-sided uniaxial pressing. The complex

L. A. Dobrza?ski; M. Drak; B. Zi?bowicz

2007-01-01

210

Effective magnetoelectric tensor of a composite material  

NASA Astrophysics Data System (ADS)

We calculate the effective magnetoelectric coefficient tensor of a composite of two single-phase magnetoelectrics in which effect of strain is unimportant. We obtain exact relations for elements of the effective magnetoelectric coefficient tensor entirely in terms of the elements of the individual components, and the composite geometry. The problem is solved by a decoupling transformation that reduces the problem to finding the effective coefficients in a composite of the same geometry but with two independent, curl-free fields. The decoupling transformation is found to be identical to that used in the problem of composite thermoelectrics footnotetextD. J. Bergman and O. Levy. Thermoelectric properties of a composite medium. J. Appl. Phys., 70:6821 - 6833, 1991. Details of the calculation will be presented.

Stroud, David; Dixit, Mehul

2013-03-01

211

Development of novel polymer\\/quasicrystal composite materials  

Microsoft Academic Search

We report on a new class of materials, polymer\\/quasicrystal composites with useful properties for beneficial exploitation in applications, such as dry bearings and composite gears. Our preliminary results indicate that our new composites are a means of enhancing the properties of certain organic polymers while providing a new means of processing quasicrystals. Al–Cu–Fe quasicrystalline materials significantly improved wear resistance to

Paul D Bloom; K. G Baikerikar; Joshua U Otaigbe; Valerie V Sheares

2000-01-01

212

Influence of material properties on the wear of composite coatings  

Microsoft Academic Search

Aluminium matrix composite (AlMC) materials are finding more and more applications in machine construction. The addition of reinforcing materials to the matrix significantly improves the composite wear resistance. However, the presence of particles of a very hard, ceramic phase (Al2O3 and SiC) increases the wear of the sliding counterpart operating against the composite. Therefore, there exists a need to find

Andrzej Posmyk

2003-01-01

213

Modeling of self-healing composite materials  

Microsoft Academic Search

In this thesis modeling approaches have been considered to describe healing process in self-healing materials. These materials can partially restore their mechanical properties as microcracks develop inside the material. The interest in modeling of self-healing materials comes from recent experiments [1] that show possible perspective applications in many fields of industry. Following the idea of bio-materials that can heal its

Alexander Dementsov

2008-01-01

214

From crabshell to chitosan-hydroxyapatite composite material via a biomorphic mineralization synthesis method.  

PubMed

Hydroxyapatite-polymer composite materials, as biological bone tissue materials, have become an important research direction. In this paper, the calcium carbonate from the crabshells was transformed into hydroxyapatite by a hydrothermal process. According to the method that we called Biomorphic Mineralization synthesis, we obtained a novel kind of hydroxyapatite-chitosan composite materials which reserved the natural perfect structure of the original crabshells. Benefited from its fine micro-structure as the crabshells, this kind of materials held a high value of tensile modulus, which is expected to be promising bone tissue engineering applications. PMID:20237825

Ge, Haoran; Zhao, Bingyuan; Lai, Yijian; Hu, Xiaobin; Zhang, Di; Hu, Keao

2010-03-17

215

Carbon-Carbon Materials - Carbon Composites Materiaux Carbone-Carbone Composites Carbones.  

National Technical Information Service (NTIS)

The application of carbon based materials in solid propellant rocket engine nozzles is discussed. Considered are polycrystalline graphites, pyrographite, carbon reinforced phenolic composites, and carbon-carbon composites. The importance of sepcarb (carbo...

C. Choury

1977-01-01

216

LOW-COST COMPOSITES IN VEHICLE MANUFACTURE - Natural-fiber-reinforced polymer composites in automotive applications  

Microsoft Academic Search

In the last decade, natural fiber composites have experienced rapid growth in the European automotive market, and this trend appears to be global in scale, provided the cost and performance is justified against competing technologies. However, mass reduction, recyclability, and performance requirements can be met today by competing systems such as injection-molded unreinforced thermoplastics; natural fiber composites will continue to

Jim Holbery; Dan Houston

2006-01-01

217

Modeling and simulation of manufacturing processes of advanced composite materials  

NASA Astrophysics Data System (ADS)

Models for autoclave curing of thermosetting matrix composites are briefly described along with models of manufacturing process models for thermoplastic matrix composites. These models can be used to obtain optimum cure cycles of composite materials. They are particularly useful since the cure cycle must be modified to account for the effect of internal heat generation at the thickness of composite laminate changes. They can be indispensable tools in finding appropriate rules for optimum cure cycles via expert systems.

Lee, Woo I.; Springer, George S.

218

Natural fiber composites with plant oil-based resin  

Microsoft Academic Search

Vacuum-assisted resin transfer molding or resin vacuum infusion process was used to make composite panels out of plant oil-based resin [acrylated epoxidized soybean oil (AESO)] and natural fiber mats made of flax, cellulose, pulp and hemp. The composites formed by room temperature cure with natural fiber reinforcement of about 10–50 wt% increased the flexural modulus to a range between 1.5

A O'Donnell; M. A Dweib; R. P Wool

2004-01-01

219

Composition and Rhetoric: A Natural Alliance.  

ERIC Educational Resources Information Center

|Writing teachers and theorists face political and pedagogical dangers because of their increasing tendency to align themselves against each other on the side of either rhetoric or composition. As the differences between the two schools widens, writing teachers stand to lose political ground in English departments and their students stand to lose…

Minot, Walter S.

220

Wear resistance of composite materials. (Latest citations from Engineered Materials abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning wear resistance of composite materials. References discuss polymer, ceramic and metal composites. Tribological testing and failure analyses are included. (Contains a minimum of 200 citations and includes a subject term index and title list.)

Not Available

1994-09-01

221

Mechanical properties of natural fibers reinforced polyester hybrid composite  

Microsoft Academic Search

In this investigation, the mechanical properties of natural fibers reinforced polyester hybrid fiber reinforced polyester\\u000a composite were analysed based on the wt % and length of the fibers. The glass fiber polyester composites were also prepared\\u000a to compare the properties. The fractured surfaces of the composite specimens were investigated using scanning electron microscopy.\\u000a The tensile and the flexural strength increases

A. Athijayamani; M. Thiruchitrambalam; V. Manikandan; B. Pazhanivel

2010-01-01

222

Structure and Properties of Teflon Composites with Natural Diamond Powders  

Microsoft Academic Search

The results of experimental investigations of the structure and properties of composites based on polytetrafluorethylene (PTFE) containing natural diamond powders (NDP) of different dispersity are presented. To obtain diamond-containing compositions for antifrictional applications, we used a preliminary mechanical treatment of NDP (40 µm) in a planetary mill. It was stated that the formation of the maximum ordered small-spherulite structure of

A. A. Okhlopkova; E. Yu. Shits

2004-01-01

223

Nano composite phase change materials microcapsules  

NASA Astrophysics Data System (ADS)

MicroPCMs with nano composite structures (NC-MicroPCMs) have been systematically studied. NC-MicroPCMs were fabricated by the in situ polymerization and addition of silver NPs into core-shell structures. A full factorial experiment was designed, including three factors of core/shell, molar ratio of formaldehyde/melamine and NPs addition. 12 MicroPCMs samples were prepared. The encapsulated efficiency is approximately 80% to 90%. The structural/morphological features of the NC-MicroPCMs were evaluated. The size was in a range of 3.4 mu m to 4.0 mu m. The coarse appearance is attributed to NPs and NPs are distributed on the surface, within the shell and core. The NC-MicroPCMs contain new chemical components and molecular groups, due to the formation of chemical bonds after the pretreatment of NPs. Extra X-ray diffraction peaks of silver were found indicating silver nano-particles were formed into an integral structure with the core/shell structure by means of chemical bonds and physical linkages. Extra functionalities were found, including: (1) enhancement of IR radiation properties; (2) depression of super-cooling, and (3) increase of thermal stabilities. The effects of SERS (Surface Enhanced Raman Spectroscopy) arising from the silver nano-particles were observed. The Raman scattering intensity was magnified more than 100 times. These effects were also exhibited in macroscopic level in the fabric coatings as enhanced IR radiation properties were detected by the "Fabric Infrared Radiation Management Tester" (FRMT). "Degree of Crystallinity" (DOC) was measured and found the three factors have a strong influence on it. DOC is closely related to thermal stability and MicroPCMs with a higher DOC show better temperature resistance. The thermal regulating effects of the MicroPCMs coatings were studied. A "plateau regions" was detected around the temperature of phase change, showing the function of PCMs. Addition of silver nano-particles to the MicroPCMs has a positive influence on it. NC-MicroPCMs with introducing silver nano particles into the MicroPCMs structure, have shown excellent multifunctional thermal properties and thermal stabilities that are far beyond those of the conventional MicroPCMs. The novel NC-MicroPCMs can be used to develop advanced smart materials and products with prosperous and promising applications in a number of industries.

Song, Qingwen

224

Reflection and transmission for layered composite materials  

NASA Astrophysics Data System (ADS)

A layered planar structure consisting of different bianisotropic materials separated by jump-immittance sheets is considered. Reflection and transmission coefficients are determined via a chain-matrix algorithm. Applications are important for radomes and radar-absorbing materials.

Graglia, Roberto D.; Uslenghi, Piergiorgio L. E.

1991-03-01

225

Review of Recent Developments. Advanced Composite Materials.  

National Technical Information Service (NTIS)

Contents: Hybrid composites, Beryllium-wire reinforced alloys by roll bonding, Transverse strength of ductile-fiber-reinforced metals, Transverse strength of brittle-fiber-reinforced alloys, Transverse strength of Al2O3-filament reinforced nickel-chromium...

K. R. Hanby

1971-01-01

226

Photorefractivity in liquid crystalline composite materials.  

National Technical Information Service (NTIS)

We report recent improvements in the photorefractive of liquid crystalline thin film composites containing electron donor and acceptor molecules. The improvements primarily result from optimization of the exothermicity of the intermolecular charge transfe...

G. P. Wiederrecht M. R. Wasielewski

1997-01-01

227

Towards the Molecular Design of Composite Materials.  

National Technical Information Service (NTIS)

The objective of this project is to develop a theory of the statistical thermodynamics at polymer blends and block copolymer systems in which the theory relates microscopic and macroscopic properties and thereby assists in the molecular design of composit...

K. F. Freed

1994-01-01

228

Environmental Fatigue Tests with Composite Materials.  

National Technical Information Service (NTIS)

Since the certification of composite airframe structures requires consideration of the effects of in service environmental conditions on fatigue and residual strength, two environmental test rigs for eight specimens were developed. Different graphite/epox...

M. Berg D. Rott H. Huth

1991-01-01

229

Thermally Conductive Structural 2D Composite Materials.  

National Technical Information Service (NTIS)

Report developed under STTR contract for topic number AF10-BT01. The recent Small Business Technology Transition (STTR) program was focused on the thermal property enhancement of polymeric composites using various functionalizations and treatments of pitc...

D. B. Curliss J. E. Lincoln J. T. Brown

2012-01-01

230

Wear behaviour of aluminium matrix composite materials  

Microsoft Academic Search

Wear behaviour of aluminium matrix composites is characterized by the dry spindle wear test under various conditions (volume\\u000a fractions of reinforcements, sliding distances and speeds). Wear resistance of composites is improved due to the presence\\u000a of reinforcements, but no noticeable improvements are observed in the wear resistance with more than 20% addition of reinforcements.\\u000a To analyse wear mechanisms, wear surfaces

C. S. Lee; Y. H. Kim; K. S. Han; T. Lim

1992-01-01

231

Tunneling and nonuniversal conductivity in composite materials  

NASA Astrophysics Data System (ADS)

A simple model based on interparticle tunneling conduction and a percolative network is shown to imply a diverging distribution of high resistors in the system. This distribution is expected to yield a nonuniversal behavior of the electrical conductivity. An experimental study of carbon black-polymer composites seems to confirm this expectation, as well as explaining why a nonuniversal behavior has not been observed in previous experimental studies on such composites.

Balberg, I.

1987-09-01

232

Gamma Spectrometric Method for Measuring Natural Radioactivity of Building Materials.  

National Technical Information Service (NTIS)

The natural exp 232 Th, exp 226 Ra and exp 40 K concentrations of building materials were determined by gamma spectrometry. Altogether 121 samples from all over Hungary, one from each factory producing building materials, were examined. The presented data...

A. Toth I. Feher

1976-01-01

233

Chemical Treatments of Natural Fiber for Use in Natural Fiber-Reinforced Composites: A Review  

Microsoft Academic Search

Studies on the use of natural fibers as replacement to man-made fiber in fiber-reinforced composites have increased and opened\\u000a up further industrial possibilities. Natural fibers have the advantages of low density, low cost, and biodegradability. However,\\u000a the main disadvantages of natural fibers in composites are the poor compatibility between fiber and matrix and the relative\\u000a high moisture sorption. Therefore, chemical

Xue Li; Lope G. Tabil; Satyanarayan Panigrahi

2007-01-01

234

Nondestructive inspection and evaluation of composite-material flywheels  

SciTech Connect

It has been demonstrated that flywheels made from composite materials are capable of storing energy with a significantly higher energy density than those made from conventional metals. Since composite materials are also very durable and inherently safer for such applications, it would appear that they will play a major role in flywheel energy-storage systems. This report addresses the question of how flywheels made from composite materials can be inspected with nondestructive test methods to establish their initial quality and their subsequent integrity during service. A variety of methods is discussed in the context of special requirements for the examination of composite flywheel structures and the results of several example nondestructive evaluations before and after spin testing are presented. Recommendations for general nondestructive testing and evaluation of composite-material flywheels are made.

Reifsnider, K.L.; Boyd, D.M.; Kulkarni, S.V.

1982-02-24

235

All natural composite sandwich beams for structural applications  

Microsoft Academic Search

As part of developing an all natural composite roof for housing application, structural panels and unit beams were manufactured out of soybean oil based resin and natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers) using vacuum assisted resin transfer molding (VARTM) technology. Physical and chemical investigations and mechanical testing of the beams yielded good results in line with desired

M. A. Dweib; B. Hu; A. O’Donnell; H. W. Shenton; R. P. Wool

2004-01-01

236

Impact of gas composition on natural gas storage by adsorption  

Microsoft Academic Search

Adsorption storage is the most promising low-pressure alternative for storing natural gas, but some operational difficulties hinder the success of this technology. From a modeling perspective, this article addresses the impact of gas composition on the cyclic behavior of adsorptive natural gas storage systems. The cyclic operation of an onboard storage reservoir is modeled as a series of consecutive two-step

José P. B. Mota

1999-01-01

237

Composite Materials Having Low Filler Percolation Thresholds and Methods of Controlling Filler Interconnectivity.  

National Technical Information Service (NTIS)

Composite materials are disclosed having low filler percolation thresholds for filler materials into the composite matrix material along with methods of controlling filler interconnectivity within the composite matrix material. Methods are, thus, disclose...

C. J. Capozzi R. Qu R. A. Gerhardt R. J. Samuels Z. Li

2006-01-01

238

Percolation and Tunneling in Composite Materials  

NASA Astrophysics Data System (ADS)

Classical percolation theory is concerned with the onset of geometrical connectivity and the accompanied onset of electrical connectivity in disordered systems. It was found, however, that in many systems, such as various composites, the geometrical and electrical onsets of the connectivity are not simultaneous and the correlation between them depends on physical processes such as tunneling. The difference between the above two types of systems and the consequences for the electrical transport properties of the latter composites have been largely ignored in the past. The application of scanning local probe microscopies and some recent theoretical developments have enabled a better understanding of the latter systems and their sometimes "strange" behavior as bona fide percolation systems. In this review we consider the above issues and their manifestation in three types of systems: Carbon Black-Polymer composites, metal-insulator cermets and hydrogenated microcrystalline silicon.

Balberg, I.; Azulay, D.; Toker, D.; Millo, O.

239

Material, process, and product design of thermoplastic composite materials  

Microsoft Academic Search

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP\\/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength

Heming Dai

2001-01-01

240

Processing of materials—monolithic to composites  

Microsoft Academic Search

A multimillion rupee 500-ton hydraulic extrusion\\/forging facility established at NPL, New Delhi, has been used to undertake\\u000a extensive studies in forming, the process of plastically deforming, which is the most important way of shaping materials.\\u000a Wrought materials are used extensively for making useful products employing extrusion and forging, the two important secondary\\u000a processing techniques used to convert materials into useful

Anil K Gupta

1995-01-01

241

Nonmetallic materials and composites at low temperatures 3  

Microsoft Academic Search

Developments in theoretical and experimental research into the use of nonmetallic materials in low temperature applications are surveyed. Studies of the thermal expansion properties of nonmetallic materials and the thermal conductivity of polymers below 1 K are reported. A method is presented for the fracture toughness of composite materials exposed to impact loading and a mini-cryostat is described for high-velocity

G. Hartwig; D. Evans

1986-01-01

242

Characterization and performance of a self-healing composite material  

Microsoft Academic Search

The development of a self-healing polymer-matrix composite material that possesses the ability to heal cracks autonomically is described. The system uses a monomer repair agent, dicyclopentadiene (DCPD), which is stored in an epoxy matrix by dispersing microcapsules containing the liquid repair agent throughout the matrix. When the material is damaged, cracks propagate through the material and break open the microcapsules,

Michael Richard Kessler

2002-01-01

243

Networks of channels for self-healing composite materials  

Microsoft Academic Search

This is a fundamental study of how to vascularize a self-healing composite material so that healing fluid reaches all the crack sites that may occur randomly through the material. The network of channels is built into the material and is filled with pressurized healing fluid. When a crack forms, the pressure drops at the crack site and fluid flows from

A. Bejan; S. Lorente; K.-M. Wang

2006-01-01

244

Left-handed materials in metallic magnetic granular composites  

Microsoft Academic Search

There is recently interests in the “left-handed” materials. In these materials the direction of the wave vector of electromagnetic radiation is opposite to the direction of the energy flow. We present simple arguments that suggests that magnetic composites can also be left-handed materials. However, the physics involved seems to be different from the original argument. In our argument, the imaginary

S. T. Chui; Z. F. Lin; L.-B. Hu

2003-01-01

245

Optical properties of polymer\\/chalcogenide glass composite materials  

Microsoft Academic Search

The novel composite material based on middle density polyethylene on one hand and thermoplastic chalcogenide glass on other hand has been worked out. Both materials used in the research are highly transparent in the middle and far IR but refraction indexes of components differ dramatically. The basic materials, polymer and glass, have close viscosities at the temperature of polyethylene processing.

Edward Bormashenko; Roman Pogreb; Semion Sutovski

2000-01-01

246

Composite materials with giant anisotropy and negative index of refraction  

Microsoft Academic Search

We demonstrate that a nanostructured plasmonic composite material can show negative index of refraction at infrared and optical frequencies. In contrast to conventional negative refraction materials, our design does not require periodicity and thus is highly tolerant to fabrication defects. Moreover, since the proposed material is intrinsically non-magnetic (mu ? 1), its performance is not limited to proximity of a

Viktor A. Podolskiy; Leo A. Alekseyev; Evgenii E. Narimanov

2005-01-01

247

Leaching of technologically enhanced naturally occurring radioactive materials.  

PubMed

A form of waste associated with mining activities is related to the type of deposit being mined and to the procedure of exploitation and enrichment adopted. The wastes usually contain relatively large amounts of technologically enhanced naturally occurring radioactive materials (TENORM). The TENORM are often stored on the surface. Consequently, they can be leached as a result of interaction with aqueous solutions of different chemical composition. This further leads to pollution of water and soil in the vicinity of the stored wastes. The paper presents the results of laboratory investigation aimed at quantifying the leaching process of samples originating from uranium dumps and storage reservoirs associated with brine pumped from coal mines. The leaching process was investigated with respect to selected elements: uranium isotopes, radium isotopes, iron, barium and sodium. The samples were exposed to aqueous solutions of different chemical composition. The experiments revealed that TENORM in form of sulphate compounds are the most resistant against leaching. The leaching coefficient for radium isotopes varies from a few thousandth percent to a few hundredth percent. On the other hand, for TENORM occurring in sand or sludge, the leaching coefficient for uranium and radium isotopes ranged from a few hundredth percent to a few percent. PMID:17482828

Chau, Nguyen Dinh; Chru?ciel, Edward

2007-03-27

248

Field-responsive smart composite particle suspension: materials and rheology  

NASA Astrophysics Data System (ADS)

Both electrorheological (ER) and magnetorheological (MR) fluids are known to be smart materials which can be rapidly and reversibly transformed from a fluid-like to a solid-like state within milliseconds by showing dramatic and tunable changes in their rheological properties under external electrical or magnetic field strength, respectively. Here, among various smart composite particles studied, recently developed core-shell structured polystyrene/graphene oxide composite based ER material as well as the dual-step functionally coated carbonyl iron composite based MR material are briefly reviewed along with their rheological characteristics under external fields.

Zhang, Wen Ling; Liu, Ying Dan; Choi, Hyoung Jin

2012-09-01

249

Elemental composition of lunar surface material.  

PubMed

Elemental abundances, so far obtained, derived from the analysis of Apollo 11 lunar material are reported. Similarities and differences exist between lunar material, the eucritic achondrites, and the augite achondrite Angra dos Reis, the analysis of which is also reported. PMID:17781474

Smales, A A; Mapper, D; Webb, M S; Webster, R K; Wilson, J D

1970-01-30

250

Advanced AE Techniques in Composite Materials Research  

Microsoft Academic Search

Advanced, waveform based acoustic emission (AE) techniques have been successfully used to evaluate damage mechanisms in laboratory testing of composite coupons. An example is presented in which the initiation of transverse matrix cracking was monitored. In these tests, broad band, high fidelity acoustic sensors were used to detect signals which were then digitized and stored for analysis. Analysis techniques were

William H. Prosser

1996-01-01

251

Composite metal foil and ceramic fabric materials  

DOEpatents

The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed. 11 figs.

Webb, B.J.; Antoniak, Z.I.; Prater, J.T.; DeSteese, J.G.

1992-03-24

252

Composite metal foil and ceramic fabric materials  

SciTech Connect

The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

Webb, Brent J. (Richland, WA); Antoniak, Zen I. (Richland, WA); Prater, John T. (Chapel Hill, NC); DeSteese, John G. (Kennewick, WA)

1992-01-01

253

Adsorption of Organic Cations to Natural Materials.  

National Technical Information Service (NTIS)

The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. The sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concent...

B. J. Brownawell H. Chen J. M. Collier J. C. Westall

1990-01-01

254

Determination of Dynamic Flexural and Shear Moduli of Thick Composite Beams Using Natural Frequencies  

Microsoft Academic Search

Based on natural frequencies, a simple and stable inverse calculation scheme for characterizing the dynamic flexural moduli, the dynamic in-plane shear modulus and the dynamic transverse shear modulus of thick fiber-reinforced composite beams is developed, and is verified by experimental testing. Expressions are derived for the errors in the characterized moduli to the geometry and material properties of the beam

K. H. Ip; P. C. Tse

2001-01-01

255

Processing of magnesia pyrochlore composites for inert matrix materials  

NASA Astrophysics Data System (ADS)

Inert matrix (IM) materials for nuclear fuel in light water reactors must meet several critical requirements that include high temperature stability, good irradiation behaviour, high thermal conductivity, and hot water corrosion resistance. MgO possesses all of the necessary requirements for an ideal IM candidate, except hot water corrosion resistance. A composite approach is being investigated in order to improve the corrosion resistance of MgO, while simultaneously taking advantage of the high thermal conductivity of MgO and its ability to be reprocessed in nitric acid. MgO pyrochlore composite compositions are fabricated based on neutronic property simulations for assessment as potential IM materials. The selected pyrochlore compositions are synthesized by both sol gel and solid state processing, and how composite processing affects the microstructure will be discussed. Among the multiple composite processing approaches investigated, ball milling produces the most homogeneous and consistent microstructures.

Yates, S. J.; Xu, P.; Wang, J.; Tulenko, J. S.; Nino, J. C.

2007-05-01

256

High temperature composite materials and magnetodielectric composites for microwave application  

NASA Astrophysics Data System (ADS)

In the part I, we investigated the microstructures, mechanical properties, and oxidation behavior of hot pressed BN in the presence of sintering additives Al2O3, Y2O3 and SiO2. BN platelets size in the sintered samples grew from ˜5 to ˜30 times for the use of all three oxides, and the use of Al2O3 and Y2O3, correspondingly. The excessive growth of BN platelets in samples containing Al2O3 and Y2O 3 caused them to misalign which, in turn, resulted in its low relative density (92.0%). The use of SiO2 mitigated this grain growth so that BN platelets aligned better to gain a higher relative density (99.5%). Flexural strength and elastic modulus of BN were proportional to their densities. Oxidation experiments conducted at 1200°C in flowing dry air showed borate glass droplets were formed on all of oxidized BN samples. The addition of SiO2 resulted in the formation of a glass layer before the appearance of these glass droplets. The presence of glass droplets was a result of the poor wetting of liquid B2O3 on BN and the dominance of the formation of B2O3 to its evaporation. Their size evolution described the "breadth figure" theory, similar to the formation of water droplets on a flat surface from the saturated water vapor air. Substructures observed inside the glass droplets contained high and consistent Al:Y atomic ratio (5:7) in all samples. The evaporation of B2O 3 isolated Al2O3, Y2O3 in the form of immiscible liquid phase to borate. In the part II, we investigated the formulation of equivalent permittivity and permeability with isotropic and anisotropic Co2Z-polymer composition. These two properties of isotropic Co2Z-LDPE/Co2Z-Silicone composites increased with Co2Z composition. However, their permittivity was always higher than that of their permeability. Permittivity and permeability of anisotropic Co2Z-Silicone composites were split into high and low values along the parallel and perpendicular directions to the alignment direction of Co2Z particles. The separation at 20 vol% Co2Z was strongest, attained 46% anisotropy so that its parallel permeability approached closer to that of its perpendicular permittivity. However, the low permittivity of Co2Z required a higher electric field to increase its particles' alignment.

Do, Thanh Ba

257

Metal oxide composite dosimeter method and material  

DOEpatents

The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

Miller, Steven D. (Richland, WA)

1998-01-01

258

Strength Criteria for Composite Materials (A Literature Survey).  

National Technical Information Service (NTIS)

Literature concerning strength (failure) criteria for composite materials is reviewed with emphasis on phenomenological failure criteria. These criteria are primarily intended to give a good estimation of the safety margin with respect to failure for arbi...

F. Roode

1982-01-01

259

Cone Calorimeter Evaluation of the Flammability of Composite Materials,  

National Technical Information Service (NTIS)

A study was undertaken to evaluate the fire performance of composite materials using the cone calorimeter as the bench-scale method of test simulating the thermal irradiance from fires of various magnitudes. Five parameters were derived from the calorimet...

J. E. Brown E. Braun W. H. Twilley

1988-01-01

260

Material Model Evaluation of a Composite Honeycomb Energy Absorber.  

National Technical Information Service (NTIS)

A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of th...

E. L. Fasanella K. E. Jackson M. A. Polanco M. S. Annett

2012-01-01

261

Materials Aspects of Fiber-Reinforced Polymer Composites in Infrastructure.  

National Technical Information Service (NTIS)

This paper provides a review of the technical literature pertaining to materials aspects of fiber-reinforced polymer (FRP) composites in infrastructural and other civil engineering applications. The main focus is placed upon the durability, chemical and m...

J. W. Chin

1996-01-01

262

Durability of composite polymer materials working in contact with pulp  

NASA Astrophysics Data System (ADS)

Composite materials were modified in order to increase their wear resistance when in contact with raw-cotton. It is found that the friction pairs increases their efficiency and durability to 2.0-2.2 times.

Abed-Negmatova, N. S.; Gulyamov, G.; Negmatov, S. S.; Hodzhikariev, D. M.; Negmatov, J. N.; Eminov, Sh. Sh.; Bozorbaev, Sh.; Aripova, A.; Negmatova, M. I.

2012-07-01

263

Smoke Production And Thermal Decomposition Products From Advanced Composite Materials.  

National Technical Information Service (NTIS)

This report describes the smoke production and thermal decomposition products from the combustion of Advanced Composite Materials (ACM) used on high performance aircraft. There are three distinct project phases with only Phase I described here. The prelim...

D. L. Courson C. D. Flemming K. J. Kuhlmann J. W. Lane J. H. Grabau

1996-01-01

264

Application of Eddy Current Techniques to Graphite Composite Materials.  

National Technical Information Service (NTIS)

Eddy current methods have been extensively applied in metals. The common characteristic for these applications is the high electrical conductivity of materials tested, higher than 1 pct. IACS (titanium). With the increasing use of graphite composite mater...

M. Alvaro V. Cortes

1991-01-01

265

Core Programs of High-Performance Composite Materials.  

National Technical Information Service (NTIS)

Evaluation of composites and components continued from the previous contract. Materials used to RTM carbon-carbon preforms were evaluated. RDS data analysis software was written and modulated DSC evaluated as an analysis tool. Bridge rehabilitation succes...

A. Crasto D. Anderson R. Esterline K. Han C. Hill

1998-01-01

266

Photorefractivity in liquid crystalline composite materials  

SciTech Connect

We report recent improvements in the photorefractive of liquid crystalline thin film composites containing electron donor and acceptor molecules. The improvements primarily result from optimization of the exothermicity of the intermolecular charge transfer reaction and improvement of the diffusion characteristics of the photogenerated ions. Intramolecular charge transfer dopants produce greater photorefractivity and a 10-fold decrease in the concentration of absorbing chromophores. The mechanism for the generation of mobile ions is discussed.

Wiederrecht, G.P. [Argonne National Lab., IL (United States); Wasielewski, M.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

1997-09-01

267

A tensile impact test apparatus for composite materials  

Microsoft Academic Search

A tensile impact test apparatus capable of applying a pure axial tensile loading to even a highly orthotropic composite material, e.g., a unidirectionally reinforced composite, was designed and constructed. Existing impact test methods such as Charpy, Izod and plate impact induce very complex stress states, making the interpretation of results difficult. Details of the apparatus design, and instrumentation problems which

D. F. Adams; L. G. Adams

1989-01-01

268

Iatrogenic tooth abrasion comparisons among composite materials and finishing techniques  

Microsoft Academic Search

Statement of Problem. Many different rotary instruments are available for shaping composite restorations. Whether use of these instruments causes undesirable iatrogenic abrasion of either the tooth surface or the composite restorative material is unknown. Assuming that damage occurs, which technique is least damaging is unknown. Purpose. This in vitro study quantified the loss of surface enamel and dentin surrounding Class

Christina A. Mitchell; Maria R. Pintado; William H. Douglas

2002-01-01

269

Chemical composition of material fractions in Danish household waste  

Microsoft Academic Search

The chemical composition of Danish household waste was determined by two approaches: a direct method where the chemical composition (61 substances) of 48 material fractions was determined after hand sorting of about 20tonnes of waste collected from 2200 households; and an indirect method where batches of 80–1200tonnes of unsorted household waste was incinerated and the content of the waste determined

Christian Riber; Claus Petersen; Thomas H. Christensen

2009-01-01

270

Embedded fibre Bragg grating sensors in advanced composite materials  

Microsoft Academic Search

Fibre Bragg grating (FBG) sensors have been embedded in a number of advanced composite materials and fibre\\/metal laminates (FMLs). The post-fabrication FBG spectra were studied to examine the influence of manufacturing variables (such as composite stacking sequence and resin flow during processing) on the final profile of the spectrum and the functionality of the FBG sensor. Distortion and broadening of

K. S. C. Kuang; R. Kenny; M. P. Whelan; W. J. Cantwell; P. R. Chalker

2001-01-01

271

Polymer?Nanoparticle Composites: Preparative Methods and Electronically Active Materials  

Microsoft Academic Search

The field of nanoparticle?polymer composites is attractive from the standpoint of integrating the key features of both polymers and nanoparticles into hybrid or composite materials. Nanocomposites geared towards electronic and photophysical targets comprise an intriguing subset of the field, and benefit from interdisciplinary efforts in nanoparticle and polymer synthesis, along with methodology that provides the dispersion, orientation, and\\/or the assembly

P. K. Sudeep; Todd Emrick

2007-01-01

272

Introduction to Composite Materials for Engineers and Technicians  

NSDL National Science Digital Library

This learning module will help instructors explain composite materials specifically for engineers and technicians. Students will learn the structure and advantages of composite materials as well as the basic processing procedures involved in their creation. It will serve as a one-lecture introduction and would be appropriate for students at the high school or college level. This document will serve as a framework for instructors and may be downloaded in PDF format.

Stuart, William J.

2012-11-08

273

Measurement of Poisson's ratio of dental composite restorative materials  

Microsoft Academic Search

The aim of this study was to determine the Poisson ratio of resin-based dental composites using a static tensile test method. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid-modified (F2000), and flowable (Filtek Flowable [FF]) composites. The Poisson ratio of the materials were determined after 1

Sew Meng Chung; Adrian U Jin Yap; Wee Kiat Koh; Kuo Tsing Tsai; Chwee Teck Lim

2004-01-01

274

Glass-Containing Composite Materials. Alternative Reinforcement Concepts  

Microsoft Academic Search

Glass-containing composites with interpenetrating, graded or layered microstructures as well as hybrid glass and glass-ceramic\\u000a matrix composites are discussed. Aspects of their fabrication, microstructural characterisation, properties and applications\\u000a are reviewed. These materials have advantages regarding ease of processing and\\/or special properties which can be achieved,\\u000a in comparison with conventional dispersion-reinforced and fibre-reinforced glasses and glass-ceramics. The use of these materials

Aldo R. Boccaccini

275

Electrolytic cut-off grinding machine for composite materials  

Microsoft Academic Search

A new cut-off machine for a composite material has been developed. The machine uses a combined system of grinding and electrolysis and it can cut off a fragile composite material consisting of metal and non-metal components. Its fundamental performance is examined on low-carbon steel and cast iron. The machine can reduce the cutting force and roughness of a finished surface

Masahiko Yoshino; Takahiro Shirakashi; Toshiyuki Obikawa; Eiji Usui

1998-01-01

276

Electromagnetic properties of dielectric and magnetic composite material for antenna  

Microsoft Academic Search

Electromagnetic properties of dielectric and magnetic composite materials were studied with various weight fractions and particle\\u000a sizes of ferrite. The composite materials were prepared through Ni-Zn spinel ferrite and silicon elastomer, and were characterized\\u000a with regard to permittivity, permeability, loss tangente, and loss tangentu. Those properties of Ni-Zn spinel ferrite were approximately 7.0, 8.4, 0.01 and 0.1 MHz to 150

Sang-Hoon Park; Won-Ki Ahn; Jun-Sig Kum; Jeong-Keun Ji; Ki-Ho Kim; Won-Mo Seong

2009-01-01

277

Hydrogen storage properties of magnesium based nanostructured composite materials  

Microsoft Academic Search

In this work, nanostructured composite materials Mg–Ni, Mg–Ni–La, Mg–Ni–Ce and Mg–LaNi5 have been synthesized using the mechanical alloying process. The new materials produced have been investigated by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscope (SEM) and electron energy dispersion spectrum (EDS) for their phase compositions, crystal structure, grain size, particle morphology and the distribution of catalyst element.

Ming Au

2005-01-01

278

Fast, Contactless Monitoring of the Chemical Composition of Raw Materials  

NASA Astrophysics Data System (ADS)

A technique to monitor chemical composition of materials during manufacturing of ceramic products, in particular - of bricks, is investigated. The technique of monitoring is likely to offset environmental pollution and save energy. For this purpose, we use the Surface photo charge effect, which is generated for each solid body interacting with electromagnetic field. The measurement is express and can be performed in-situ in production conditions. The experimental work has shown that different samples of the investigated materials with different compositions produce different signals specific to each sample. For the same material, the signal varies with the change in chemical composition. More specifically, it is shown that for the material from which the bricks are fired, the signal is a function of the percentage of coal sludge. The results indicate that the characterization technique as a viable technique for control of incoming raw materials.

Ivanov, O.; Stoyanov, Zh.; Stoyanov, B.; Nadoliisky, M.; Vaseashta, Ashok

279

Composite material stub-blade wing joint  

NASA Astrophysics Data System (ADS)

The viability of a composite stub-blade wing joint for high-altitude long-endurance aircraft was investigated in a joint-design study. The results of an analysis show that the resulting joint design is capable of carrying moderately high bending, shear, and torsional loads. The stub-blade wing joint design is weight-competitive with the traditional tension-type wing joint. In addition, it offers attractive features such as the ease of assembly and disassembly, the ease of fabrication, and an aerodynamic smoothness.

Franklin, Walter M.; Kreimendahl, Bryan W.

280

Natural rubber composites as thermal neutron radiation shields  

Microsoft Academic Search

Different amounts of boric acid (H3BO3) were mixed with a conductive natural rubber (loaded with 40 phr of HAF carbon black) to get thermal neutron radiation shielding composites. It was found that the total macroscopic cross-section reaches 0.29 cm?1 at 30 phr of H3BO3. The dependence of thermal and electrical properties of such composites on the concentration of H3BO3 was

S. E Gwaily; H. H Hassan; M. M Badawy; M Madani

2002-01-01

281

Fracture and fatigue of natural fiber-reinforced cementitious composites  

Microsoft Academic Search

This paper presents the results of an experimental study of resistance-curve behavior and fatigue crack growth in cementitious matrices reinforced with eco-friendly natural fibers obtained from agricultural by-products. The composites include: blast furnace slag cement reinforced with pulped fibers of sisal, banana and bleached eucalyptus pulp, and ordinary Portland cement composites reinforced with bleached eucalyptus pulp. Fracture resistance (R-curve) and

H. Savastano Jr.; S. F. Santos; M. Radonjic; W. O. Soboyejo

2009-01-01

282

New Kind of Super-Hybrid Composite Material for Civil Use-Ramie Fibre/Al.  

National Technical Information Service (NTIS)

A new super-hybrid composite material has been developed in which ramie, a natural plant fiber, is chosen as reinforcement because of its high strength and low price. In the present study, industrial aluminum sheets were sandwiched with ramie fiber prepre...

S. Li B. Zhou Q. Zeng X. Bao

1994-01-01

283

Quality control materials in food composition databanks  

Microsoft Academic Search

Reference materials (RMs) have emerged with the aim of improving analytical methods performance, in what regards to their validation, calibration, uncertainty, training and internal quality control, and of increasing the comparability of measurements between laboratories. Due to their unquestionable importance, but still low availability and high cost, the present work has determined the suitability of infant formula, powdered garlic, tea

I. Castanheira; C. Abrantes; M. Batista; I. Coelho; A. Sanches-Silva

2009-01-01

284

Composition and process for making an insulating refractory material  

DOEpatents

A composition and process for making an insulating refractory material. The composition includes calcined alumina powder, flash activated alumina powder, an organic polymeric binder and a liquid vehicle which is preferably water. Starch or modified starch may also be added. A preferred insulating refractory material made with the composition has a density of about 2.4-2.6 g/cm.sup.3 with reduced thermal conductivity, compared with tabular alumina. Of importance, the formulation has good abrasion resistance and crush strength during intermediate processing (commercial sintering) to attain full strength and refractoriness, good abrasion resistance and crush strength.

Pearson, Alan (Murrysville, PA); Swansiger, Thomas G. (Apollo, PA)

1998-04-28

285

Factors affecting the isotopic composition of organic matter. (1) Carbon isotopic composition of terrestrial plant materials.  

PubMed

The stable isotope composition of the light elements (i.e., H, C, N, O and S) of organic samples varies significantly and, for C, is also unique and distinct from that of inorganic carbon. This is the result of (1) the isotope composition of reactants, (2) the nature of the reactions leading to formation and post-formational modification of the samples, (3) the environmental conditions under which the reactions took place, and (4) the relative concentration of the reactants compared to that of the products (i.e., [products]/[reactants] ratio). This article will examine the carbon isotope composition of terrestrial plant materials and its relationship with the above factors. delta13C(PDB) values of terrestrial plants range approximately from -8 to -38%, inclusive of C3-plants (-22 to -38%), C4-plants (-8 to -15%) and CAM-plants (-13 to -30%). Thus, the delta13C(PDB) values largely reflect the photosynthesis pathways of a plant as well as the genetics (i.e., species difference), delta13C(PDB) values of source CO2, relevant humidity, CO2/O2 ratios, wind and light intensity etc. Significant variations in these values also exist among different tissues, different portions of a tissue and different compounds. This is mainly a consequence of metabolic reactions. Animals mainly inherit the delta13C(PDB) values of the foods they consume; therefore, their delta13C(PDB) values are similar. The delta13C(PDB) values of plant materials, thus, contain information regarding the inner workings of the plants, the environmental conditions under which they grow, the delta13C(PDB) values of CO2 sources etc., and are unique. Furthermore, this uniqueness is passed on to their derivative matter, such as animals, humus etc. Hence, they are very powerful tools in many areas of research, including the ecological and environmental sciences. PMID:11480769

Yeh, H W; Wang, W M

2001-07-01

286

Personal care compositions comprising a zinc containing material in an aqueous surfactant composition  

US Patent & Trademark Office Database

Disclosed are compositions comprising an effective amount of a zinc containing material having an aqueous solubility within the composition of less than about 25% by weight at 25.degree. C.; from about 5% to about 50% of a surfactant; and from about 40% to about 95% water; wherein the pH of the composition is greater than about 7. Further disclosed are compositions comprising an effective amount of a zinc containing material having an aqueous solubility within the composition of less than about 25% by weight at 25.degree. C.; from about 5% to about 50% of a surfactant; and from about 0.1% to about 5% of a zinc ionophoric material; from about 40% to about 95% water; and wherein the pH of the composition is greater than about 7.

2012-02-21

287

Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance  

SciTech Connect

Composite cathode materials in lithium ion batteries have become the subject of a great amount of research recently as cost and safety issues related to LiCoO2 and other layered structures have been discovered. Alternatives to these layered materials include materials with the spinel and olivine structures, but these present different problems, e.g. spinels have low capacities and cycle poorly at elevated temperatures, and olivines exhibit extremely low intrinsic conductivity. Previous work has shown that composite structures containing spinel and layered materials have shown improved electrochemical properties. These types of composite structures have been studied in order to evaluate their performance and safety characteristics necessary for use in lithium ion batteries in portable electronic devices, particularly hybrid-electric vehicles. In this study, we extended that work to layered-olivine and spinel-olivine composites. These materials were synthesized from precursor salts using three methods: direct reaction, ball-milling, and a coreshell synthesis method. X-ray diffraction spectra and electrochemical cycling data show that the core-shell method was the most successful in forming the desired products. The electrochemical performance of the cells containing the composite cathodes varied dramatically, but the low overpotential and reasonable capacities of the spinel-olivine composites make them a promising class for the next generation of lithium ion battery cathodes.

Ward, R.M.; Vaughey, J.T.

2006-01-01

288

Accelerated hygrothermal stabilization of composite materials  

SciTech Connect

Experimentation validated a simple moisture conditioning scheme to prepare Gr/Ep composite parts for precision applications by measuring dimensional changes over 90 days. It was shown that an elevated temperature moisture conditioning scheme produced a dimensionally stable part from which precision structures could be built/machined without significant moisture induced dimensional changes after fabrication. Conversely, that unconditioned Gr/Ep composite panels exhibited unacceptably large dimensional changes (i.e., greater than 125 ppM). It was also shown that time required to produce stable parts was shorter, by more than an order of magnitude, employing the conditioning scheme than using no conditioning scheme (46 days versus 1000+ days). Two final use environments were chosen for the experiments: 50% RH/21C and 0% RH/21C. Fiberite 3034K was chosen for its widespread use in aerospace applications. Two typical lay-ups were chosen, one with low sensitivity to hygrothermal distortions and the other high sensitivity: [0, {plus_minus} 45, 90]s, [0, {plus_minus} 15, 0]s. By employing an elevated temperature, constant humidity conditioning scheme, test panels achieved an equilibrium moisture content in less time, by more than an order of magnitude, than panels exposed to the same humidity environment and ambient temperature. Dimensional changes, over 90 days, were up to 4 times lower in the conditioned panels compared to unconditioned panels. Analysis of weight change versus time of test coupons concluded that the out-of-autoclave moisture content of Fiberite 3034K varied between 0.06 and 0.1%.

Gale, J.A.

1994-05-01

289

Data analysis techniques for impact tests of composite materials  

Microsoft Academic Search

This paper discusses data analysis techniques for instrumented impact tests conducted on glass fiber composite materials. For this study, a drop weight tower has been instrumented with an accelerometer and computer data acquisition system. From the acceleration data obtained, load, energy, velocity, and displacement are calculated in a spreadsheet environment. The resulting data from multiple tests for each material type

A. L. Svenson; M. W. Hargrave; B. S. Ye; L. C. Bank

1994-01-01

290

Impact damage processes in composite sheet and sandwich honeycomb materials  

Microsoft Academic Search

The research interest of this study is the impact toughness of different lightweight sandwich panels and composite sheet materials. This is as to the degrees of damage inflicted on the contact surface, through-thickness and rear surface of the materials when subjected to different impacts. For this study, specimens were prepared from sheet moulding compound (SMC), glass mat thermoplastic (GMT) and

J. P. Dear; H. Lee; S. A. Brown

2005-01-01

291

Measurement of Damping of Composite Materials for Turbomachinery Applications.  

National Technical Information Service (NTIS)

The scientific community has felt that ceramic matrix composite (CMC) materials possess more material damping than the superalloys used in the production of rocket engine turbomachinery turbine-end components. The purpose of this NASA/MFSC study is to qua...

D. L. Harris

1998-01-01

292

Experimental techniques for dynamic characterization of composite materials  

SciTech Connect

This research combines theoretical and experimental approaches for dynamic material characterization of composite materials. The samples studied include continuous fiber graphite/epoxy beams with various symmetric lay-up configurations. Included are laminated beams with the following lay-ups: [0[sub 8]/90[sub 8

Greif, R. (Tufts Univ., Medford, MA (United States). Dept. of Mechanical Engineering); Hebert, B. (Cambridge Collaborative, Inc., MA (United States))

1995-01-01

293

Polymer-based composite materials in general industrial fields  

Microsoft Academic Search

An overview of material research and product development for polymer-based composite materials since the 1950s in Japanese general industrial use is given. This progress is divided into four steps, each lasting about one decade; the trends of the fourth period (1984-today), following the third, transition period, are emphasised. In addition, as a future perspective, the possibility of development of intelligent

Tatsuo Ogasa; Jun Takahashi; Kiyoshi Kemmochi

1995-01-01

294

DOE Automotive Composite Materials Research: Present and Future Efforts  

Microsoft Academic Search

One method of increasing automotive energy efficiency is through mass reduction of structural components by the incorporation of composite materials. Significant use of glass reinforced polymers as structural components could yield a 20--30% reduction in vehicle weight while the use of carbon fiber reinforced materials could yield a 40--60% reduction in mass. Specific areas of research for lightweighting automotive components

1999-01-01

295

Effective mechanical, transport and cross properties for distressed composite materials  

Microsoft Academic Search

Composite materials and materials that have been subjected to varying level of damage have been the subject of extensive research for several decades especially with regard to prediction of constitutive behavior. Classical homogenization techniques aim at replacing an actual heterogeneous body by a fictitious homogeneous solid, which globally behaves in the same way. In this thesis, we are considering the

Morteza Eskandari-Ghadi

2003-01-01

296

Thermographic investigation of sandwich structure made of composite material  

Microsoft Academic Search

In this paper an experimental procedure, by means of thermographic technique, was set up in order to detect some typical defects, which could be found in composite material sandwich structures. The material thermal response was investigated for different artificially defects inserted in some specimens; every kind of defect was listed. Then the experimental procedure was applied to study a wind-turbine

V. Dattoma; R. Marcuccio; C. Pappalettere; G. M. Smith

2001-01-01

297

A Novel Non-Halogenated Flame Retardant for Composite Materials  

Microsoft Academic Search

Flame retardants, such as inorganic fillers or halogenated resins, are incorporated into composites either as additives or reactive materials. In order to improve processability and mechanical properties, as well as reduce smoke toxicity, a method is being developed to introduce highly effective, inexpen- sive flame retardant materials into thermoset resins. Superabsorbent polymers (SAP) can be loaded with inexpensive inorganic phosphates

Martin Rogers; Lisa Sterner; Thomas Amos; Ayesha Johnson

298

Natural-fiber-reinforced polymer composites in automotive applications  

Microsoft Academic Search

In the past decade, natural-fiber composites with thermoplastic and thermoset matrices have been embraced by European car\\u000a manufacturers and suppliers for door panels, seat backs, headliners, package trays, dashboards, and interior parts. Natural\\u000a fibers such as kenaf, hemp, flax, jute, and sisal offer such benefits as reductions in weight, cost, and CO2, less reliance on foreign oil sources, and recyclability.

James Holbery; Dan Houston

2006-01-01

299

Collagen/hydroxyapatite composite materials with desired ceramic properties.  

PubMed

Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5 g/cm(3) while the porosity varies from 96.5% down to 27.5%. PMID:21415027

Andronescu, Ecaterina; Voicu, Georgeta; Ficai, Maria; Mohora, Ioana Anita; Trusca, Roxana; Ficai, Anton

2011-03-16

300

Bio-mimetic mechanisms of natural hierarchical materials: a review.  

PubMed

Natural selection and evolution develop a huge amount of biological materials in different environments (e.g. lotus in water and opuntia in desert). These biological materials possess many inspiring properties, which hint scientists and engineers to find some useful clues to create new materials or update the existing ones. In this review, we highlight some well-studied (e.g. nacre shell) and newly-studied (e.g. turtle shell) natural materials, and summarize their hierarchical structures and mechanisms behind their mechanical properties, from animals to plants. These fascinating mechanisms suggest to researchers to investigate natural materials deeply and broadly, and to design or fabricate new bio-inspired materials to serve our life. PMID:23332379

Chen, Qiang; Pugno, Nicola M

2012-11-17

301

Method of forming a composite material having improved bond strength  

SciTech Connect

A composite material having improved bond strength and a substantially smooth external surface comprises a deoxidized copper alloy core material and a copper-aluminum-silicon clad material. The composite is formed by rolling together the core and clad, preferably in an unheated condition, in a single pass with a reduction of about 50% to 75% to form a metallurgical bond between the core and clad and thereafter enhancing the bond strength by heating the bonded core and cladding to a temperature in the range of about 200/sup 0/ C. to about 750/sup 0/ C. for a time period of about 5 minutes to about 24 hours.

Breedis, J.F.; Fister, J.C.

1985-02-19

302

DOE Automotive Composite Materials Research: Present and Future Efforts  

SciTech Connect

One method of increasing automotive energy efficiency is through mass reduction of structural components by the incorporation of composite materials. Significant use of glass reinforced polymers as structural components could yield a 20--30% reduction in vehicle weight while the use of carbon fiber reinforced materials could yield a 40--60% reduction in mass. Specific areas of research for lightweighting automotive components are listed, along with research needs for each of these categories: (1) low mass metals; (2) polymer composites; and (3) ceramic materials.

Warren, C.D.

1999-08-10

303

Characterization of cryogenic microcracking in carbon fiber/epoxy composite materials  

NASA Astrophysics Data System (ADS)

Polymeric composite materials have been widely utilized to take advantage of their large specific strength and stiffness. These characteristics have made them attractive for use in aerospace applications as containment structures for cryogenic fluids. However, the anisotropic, heterogeneous, and viscoelastic nature of polymeric composite materials creates a unique set of challenges for the storage of cryogenic fluids. Mismatches in thermal expansion between the fibers and the matrix in these materials result in the generation of thermal stresses at low temperatures that can ultimately cause failure in the form of microcracks that propagate throughout the material, degrading performance. This work examined the phenomenological and theoretical aspects of microcrack formation in carbon fiber/epoxy composite materials at low temperatures. Microcrack formation was initially investigated using an experimental approach. The role of the fiber and matrix type in microcracking was studied, along with the interaction between the fibers and the matrix and the effects of nanoparticle matrix modification. It was found that the fiber and matrix type had significant effects on microcrack formation, with decreased fiber moduli, decreased matrix coefficient of thermal expansion, nanoparticle modification, rubber toughening, and increased adhesion all corresponding to reduced microcracking. These improvements were achieved by reducing the thermal stresses in the materials studied and increasing the failure resistance of the laminates. It was found that the processing conditions of a laminate, namely the cure temperature, had a direct impact on microcracking by changing the stress free temperature of a material and the corresponding thermal stresses at cryogenic temperatures. The analysis of the variables that contributed to microcrack formation was used to develop a stress-based compound beam model to predict the onset temperature for microcracking in composite materials. This model was unique in that it accounted for the variation in material properties at low temperatures. Collectively, this work examined the phenomena behind the cryogenic microcracking of composite materials and applied this information to develop a predictive model for low temperature failure of composite materials from thermal stress generation.

Timmerman, John Francis

304

Bioactive ceramic composite materials in hydroxyapatite-tricalcium phosphate system  

Microsoft Academic Search

Materials in hydroxyapatite-tricalcium phosphate systems are promising for the use in cell technologies for regeneration of\\u000a damaged bone tissue. The results of investigations of the influence of the synthesis conditions on the phase composition of\\u000a materials and the formation of their structure and properties upon baking of powders are given. The parameters of the process\\u000a of preparation of materials with

O. L. Kubarev; V. S. Komlev; S. M. Barinov

2010-01-01

305

The Yeh-Stratton Criterion for Composite Materials  

Microsoft Academic Search

A new criterion for composite failure is proposed based on the Yeh Stratton (Y-S) criterion which is proven to work well for isotropic materials. Since the Y-S criterion requires three yield strengths from simple tension, compression, and torsion tests, the Y-S criterion can be applicable for ductile materials as well as brittle materials with different strengths in tension and compression.

Hsien-Yang Yeh; Chang H. Kim

1994-01-01

306

Modern composite materials manufa- ctured by pressure infiltration method  

Microsoft Academic Search

Purpose: The purpose of this paper is to present the technique of manufacturing the composite materials based on porous ceramic preforms infiltrated by liquid aluminium alloy and examination of the structure and corrosion resistance of those materials. Design\\/methodology\\/approach: The material for investigations was manufactured by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC - AlSi12

L. A. Dobrza?ski; M. Kremzer; M. Drak

307

Quantitative measurement of nanomechanical properties in composite materials  

NASA Astrophysics Data System (ADS)

In this work, quantitative Atomic force acoustic microscopy (AFAM) was used to measure nanomechanical properties and to determine microstructural morphology in fiber reinforced composites and hard calcified tissue. In carbon fiber reinforced composites, the fiber-matrix interphase is of interest as it affects the primary load-transfer process and thereby bulk mechanical properties of reinforced composites. The study of properties in the interphase region is important for an understanding of the bulk mechanical properties, which have been shown affected by moisture-based environmental degradation. Single point AFAM testing has been used to quantitatively determine elastic properties at the fiber-matrix interphase by taking advantage of the high spatial scanning resolution capable of measuring interphase dimensions. Carbon-fiber epoxy composite samples were degraded in laboratory conditions by exposure to a accelerated hydrothermal degradation environment in deionized water and salt water. Composite degradation has been characterized by the change in the epoxy matrix contact stiffness and the interphase properties. A decrease in matrix stiffness was found to coincide with the environmental exposure and moisture absorption of the samples. Interphase stiffness measurements indicate a constant interphase thickness as a function of environmental exposure. Chemical analysis of the epoxy using FTIR and Raman spectroscopy indicate hydrolysis of the C-O-C and Epoxide bonds which contribute to the decrease in epoxy mechanical properties. Accelerated degradation by salt water and deionized water both resulted in degradation of the epoxy, though the presence of sodium chloride showed less degradation. From SEM, debonding of the fiber-matrix interface was observed to be more severe when exposed to a salt water environment. In performing quantitative AFAM measurements, the effects of tip shape on the contact mechanics at the epoxy interface were found to influence the reported results significantly, and new, power-law body of revolution models of the probe tip geometry have been applied. Due to the low yield strength of polymers compared with other engineering materials, elastic-plastic contact is considered to better represent the epoxy surface response and was used to acquire more accurate quantitative measurements. Visco-elastic contact response was introduced in the boundary condition of the AFAM cantilever vibration model, due to the creep nature of epoxy, to determine time-dependent effects. These methods have direct impact on the quantitative measurement capabilities of near-filler interphase regions in polymers and composites and the long-term influence of environmental conditions on composites. In addition, quantitative AFAM scans were made on distal surfaces of human bicuspids and molars, to determine the microstructural and spatial variation in nanomechanical properties of the enamel biocomposite. Single point AFAM measurements were performed on individual enamel prism and sheath locations to determine spatial elastic modulus. Mechanical property variation of enamel is associated to the differences in the mineral to organic content and the apatite crystal orientations within the enamel microstructure. Also, variation in the elastic modulus of the enamel ultrastructure was observed in measurements at the outer enamel versus near the dentine enamel junction (DEJ).

Zhao, Wei

308

Ultrasonic guided wave mechanics for composite material structural health monitoring  

NASA Astrophysics Data System (ADS)

The ultrasonic guided wave based method is very promising for structural health monitoring of aging and modern aircraft. An understanding of wave mechanics becomes very critical for exploring the potential of this technology. However, the guided wave mechanics in complex structures, especially composite materials, are very challenging due to the nature of multi-layer, anisotropic, and viscoelastic behavior. The purpose of this thesis is to overcome the challenges and potentially take advantage of the complex wave mechanics for advanced sensor design and signal analysis. Guided wave mechanics is studied in three aspects, namely wave propagation, excitation, and damage sensing. A 16 layer quasi-isotropic composite with a [(0/45/90/-45)s]2 lay up sequence is used in our study. First, a hybrid semi-analytical finite element (SAFE) and global matrix method (GMM) is used to simulate guided wave propagation in composites. Fast and accurate simulation is achieved by using SAFE for dispersion curve generation and GMM for wave structure calculation. Secondly, the normal mode expansion (NME) technique is used for the first time to study the wave excitation characteristics in laminated composites. A clear and simple definition of wave excitability is put forward as a result of NME analysis. Source influence for guided wave excitation is plotted as amplitude on a frequency and phase velocity spectrum. This spectrum also provides a guideline for transducer design in guided wave excitation. The ultrasonic guided wave excitation characteristics in viscoelastic media are also studied for the first time using a modified normal mode expansion technique. Thirdly, a simple physically based feature is developed to estimate the guided wave sensitivity to damage in composites. Finally, a fuzzy logic decision program is developed to perform mode selection through a quantitative evaluation of the wave propagation, excitation and sensitivity features. Numerical simulation algorithms are validated with both finite element analyses and laboratory experiments. For the quasi-isotropic composite, it is found that the ultrasonic wave propagation characteristics are not always quasi-isotropic. The directional dependence is very significant at high frequency and higher order wave modes. Mode separation between Rayleigh-Lamb type and Shear Horizontal type guided waves is not possible. In addition, guided wave modes along one dispersion curve line could have a significant difference in wave structure. Therefore, instead of using traditional symmetric, antisymmetric, and SH notation, a new notation is used to identify the dispersion curves in a numerical order. Wave modes with a skew angle larger than 30 degrees can exist in a quasi-isotropic composite plate, which is validated by both FEM and experiment. At low frequency, the first wave mode has higher sensitivity than that of the third wave mode. However, the attenuation of the first wave mode is higher than that of the third wave mode. The mode selection trade-offs are evaluated and recommendations are provided for guided waves used in long range structural health monitoring.

Gao, Huidong

309

Molecular interactions in inorganic-organic composite materials  

NASA Astrophysics Data System (ADS)

Inorganic-organic interactions play a key role in determining the molecular and macroscopic properties of resulting composites. These materials have a wide variety of applications including use as catalysts, hosts for optical and electronic applications, and as adsorbents. Tailoring composites for each unique application is accomplished using local interactions between inorganic and organic species to control both local and mesoscopic ordering. For many inorganic-organic composites, no local order exists thereby inhibiting local characterization of these materials using diffraction techniques. However, using NMR methods that are not dependent upon periodicity, unique insight about inorganic-organic interactions in locally amorphous materials can be achieved. Using solid-state NMR methods, inorganic-organic interactions have been utilized to unambiguously establish the local organization of a variety of mesoporous materials as well as provide insight into the biological processes controlling biomineralization. For example, such experiments have revealed the location and coordination of aluminum species in the aluminosilicate framework of mesoporous materials. Such findings are crucial for the preparation of advanced catalytically active materials. These techniques have also provided increase understanding of the formation process of the inorganic network and have lead to the synthesis of the first mesophase material with a 2D crystalline architecture. This discovery is promising for enhancing the thermal and mechanical strength of mesoporous catalysts that had previously been locally disordered and thermally unstable. These investigations provide a wealth of knowledge for understanding the influence organic molecules exert upon silica structures and can be utilized to provide advanced, tailored composites.

Christiansen, Sean Condon

310

Development of composite tissue scaffolds containing naturally sourced mircoporous hydroxyapatite  

Microsoft Academic Search

The aims of this work were to investigate the conversion of a marine alga into hydroxyapatite (HA), and furthermore to design a composite bone tissue engineering scaffold comprising the synthesised HA within a porous bioresorbable polymer. The marine alga, Phymatolithon calcareum, which exhibits a calcium carbonate honeycomb structure, with a natural architecture of interconnecting permeable pores (microporosity 4–11?m), provided the

F. Kusmanto; G. Walker; Q. Gan; P. Walsh; F. Buchanan; G. Dickson; M. McCaigue; C. Maggs; M. Dring

2008-01-01

311

Hierarchically biomimetic bone scaffold materials: nano-HA/collagen/PLA composite.  

PubMed

A bone scaffold material (nano-HA/ collagen/PLA composite) was developed by biomimetic synthesis. It shows some features of natural bone both in main composition and hierarchical microstructure. Nano-hydroxyapatite and collagen assembled into mineralized fibril. The three-dimensional porous scaffold materials mimic the microstructure of cancellous bone. Cell culture and animal model tests showed that the composite material is bioactive. The osteoblasts were separated from the neonatal rat calvaria. Osteoblasts adhered, spread, and proliferated throughout the pores of the scaffold material within a week. A 15-mm segmental defect model in the radius of the rabbit was used to evaluate the bone-remodeling ability of the composite. Combined with 0.5 mg rhBMP-2, the material block was implanted into the defect. The segmental defect was integrated 12 weeks after surgery, and the implanted composite was partially substituted by new bone tissue. This scaffold composite has promise for the clinical repair of large bony defects according to the principles of bone tissue engineering. PMID:15116405

Liao, S S; Cui, F Z; Zhang, W; Feng, Q L

2004-05-15

312

Mesoporous MFI zeolite material from silica–alumina\\/epoxy-resin composite material and its catalytic activity  

Microsoft Academic Search

Although the versatilities of zeolitic materials are widely known to chemists and materials scientists, their exclusive microporosity sometimes causes various defections especially in the diffusion of reactant and product molecules in catalytic reactions. Silica–alumina\\/epoxy-resin composite materials were obtained from TMOS (tetramethoxysilane), aluminum acetylacetonate and bisphenol A diglycidyl ether with a cyclic acid anhydride as both condensation and curing reagents. Hydrothermal

Masahiro Fujiwara; Akinori Sakamoto; Kumi Shiokawa; Astam K. Patra; Asim Bhaumik

2011-01-01

313

Materials characterization center workshop on compositional and microstructural analysis of nuclear waste materials. Summary report  

Microsoft Academic Search

The purpose of the Workshop on Compositional and Microstructural Analysis of Nuclear Waste Materials, conducted November 11 and 12, 1980, was to critically examine and evaluate the various methods currently used to study non-radioactive, simulated, nuclear waste-form performance. Workshop participants recognized that most of the Materials Characterization Center (MCC) test data for inclusion in the Nuclear Waste Materials Handbook will

J. L. Daniel; D. M. Strachan; J. W. Shade; M. T. Thomas

1981-01-01

314

Thermal, mechanical, and electroelastic behavior of composite materials  

SciTech Connect

A unified analytical approach is developed to predict the effective behavior of composite materials for electronic applications. The target applications are materials for electronic packaging and electromechanical transducers where the material properties of interest are the effective thermal expansion coefficients, thermal conductivity, dielectric constant, and the couples electroelastic behavior. The analytical approach that is forwarded is based on the equivalent inclusion method of Eshelby (1957) extended to finite reinforcement concentrations through the Mori-Tanaka (1973) mean field approach. In addition to the effects of the material properties of the constituents, the effects of the volume fraction, shape, and orientation distribution of the reinforcing phase are considered. Through this approach, internal stresses generated due to the mismatch in thermal expansion coefficients of the constituents of a composite material are studied. Thermal expansion coefficients and time dependent creep deformations under a constant applied stress are analyzed. Analytical predictions of the proposed model are seen to be in good agreement with measured results of a multiphase Al2O3/Si3N4/Kerimid composite. The Mori-Tanaka mean field approach is also utilized to study the effective physical properties, modeled by Laplace's equation, of composite materials. Particular attention is devoted to microdamaged composites containing porosity or microcracks in the matrix and composites with coated reinforcement. Analytical predictions are shown to be in good agreement with measured results of the effective thermal conductivity for a multiphase Al2O3/Si3N4/Kerimid composite. Finally, the rigorous analytical solution for the couples electroelastic behavior of piezoelectric inclusions (Deeg, 1980) is utilized to derive the constraint tensors for an ellipsoidal piezoelectric inclusion in a infinite matrix.

Dunn, M.L.

1992-01-01

315

Review on advanced composite materials boring mechanism and tools  

NASA Astrophysics Data System (ADS)

With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher specific strength and higher specific modulus than glass fibre reinforced resin composites of the 1st generation. They are widely used in aviation and aerospace industry due to their high specific strength, high specific modulus, excellent ductility, anticorrosion, heat-insulation, sound-insulation, shock absorption and high&low temperature resistance. They are used for radomes, inlets, airfoils(fuel tank included), flap, aileron, vertical tail, horizontal tail, air brake, skin, baseboards and tails, etc. Its hardness is up to 62~65HRC. The holes are greatly affected by the fibre laminates direction of carbon fibre reinforced composite material due to its anisotropy when drilling in unidirectional laminates. There are burrs, splits at the exit because of stress concentration. Besides there is delamination and the hole is prone to be smaller. Burrs are caused by poor sharpness of cutting edge, delamination, tearing, splitting are caused by the great stress caused by high thrust force. Poorer sharpness of cutting edge leads to lower cutting performance and higher drilling force at the same time. The present research focuses on the interrelation between rotation speed, feed, drill's geometry, drill life, cutting mode, tools material etc. and thrust force. At the same time, holes quantity and holes making difficulty of composites have also increased. It requires high performance drills which won't bring out defects and have long tool life. It has become a trend to develop super hard material tools and tools with special geometry for drilling composite materials.

Shi, Runping; Wang, Chengyong

2010-12-01

316

Annual Conference on Composites and Advanced Ceramic Materials  

SciTech Connect

The proceedings examine current status and future prospects for engineering ceramics and discuss topics on the reinforcements and interfaces of ceramic-matrix composites, the oxide-matrix and nonoxide-matrix composites, and the fracture and mechanical behaviors in ceramic matrix composites. Papers are presented on an Air Force high-temperature materials program, a high-temperature continuous sintered SiC fiber for composite applications, silylene-acetylene polymers as precursors to SiC fibers, the material characterization of chemical-vapor-deposited TiB2 fibers, and an investigation of interfacial shear strength in SiC/Si3N4 composites. Attention is also given to an evaluation of SiC platelets as a reinforcement for oxide matrix composites, physical properties of alumina-boron carbide whisker/particle composites, hot isostatic pressing of sintered Si3N4 ceramics, the influence of the Si3N4 microstructure on its R-curve and fatigue behavior, and acoustic emission characterization of the fracture mechanism of a glass-matrix composite.

Not Available

1991-10-01

317

Development of chemical vapor composites, CVC materials. Final report  

SciTech Connect

Industry has a critical need for high-temperature operable ceramic composites that are strong, non-brittle, light weight, and corrosion resistant. Improvements in energy efficiency, reduced emissions and increased productivity can be achieved in many industrial processes with ceramic composites if the reaction temperature and pressure are increased. Ceramic composites offer the potential to meet these material requirements in a variety of industrial applications. However, their use is often restricted by high cost. The Chemical Vapor composite, CVC, process can reduce the high costs and multiple fabrication steps presently required for ceramic fabrication. CVC deposition has the potential to eliminate many difficult processing problems and greatly increase fabrication rates for composites. With CVC, the manufacturing process can control the composites` density, microstructure and composition during growth. The CVC process: can grow or deposit material 100 times faster than conventional techniques; does not require an expensive woven preform to infiltrate; can use high modulus fibers that cannot be woven into a preform; can deposit composites to tolerances of less than 0.025 mm on one surface without further machining.

NONE

1998-10-05

318

The Cost of Automotive Polymer Composites: A Review and Assessment of DOE's Lightweight Materials Composites Research  

SciTech Connect

Polymer composite materials have been a part of the automotive industry for several decades, with early application in the 1953 Corvette. These materials have been used for applications with low production volumes, because of their shortened lead times and lower investment costs relative to conventional steel fabrication. Important drivers of the growth of polymer composites have been the reduced weight and parts consolidation opportunities the material offers, as well as design flexibility, corrosion resistance, material anisotropy, and mechanical properties. Although these benefits are well recognized by the industry, polymer composite use has been dampened by high material costs, slow production rates, and to a lesser extent, concerns about recyclability. Also impeding large scale automotive applications is a curious mixture of concerns about material issues such as crash energy absorption, recycling challenges, competitive and cost pressures, the industry's general lack of experience and comfort with the material, and industry concerns about its own capabilities (Flynn and Belzowski 1995). Polymer composite materials are generally made of two or more material components--fibers, either glass or carbon, reinforced in the matrix of thermoset or thermoplastic polymer materials. The glass-reinforced thermoset composites are the most commonly used composite in automotive applications today, but thermoplastic composites and carbon fiber-reinforced thermosets also hold potential. It has been estimated that significant use of glass-reinforced polymers as structural components could yield a 20-35% reduction in vehicle weight. More importantly, the use of carbon fiber-reinforced materials could yield a 40-65% reduction in weight.

Das, S.

2001-01-26

319

Fabrication of a nanostructured gold-polymer composite material  

NASA Astrophysics Data System (ADS)

A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent for both the AP and the water solution of HAuCl4. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the reduction of AuCl4- results in the formation of gold nanoparticles (˜ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the composite material.

Mallick, K.; Witcomb, M.; Scurrell, M.

2006-07-01

320

Probabilistic fatigue life prediction of metallic and composite materials  

NASA Astrophysics Data System (ADS)

Fatigue is one of the most common failure modes for engineering structures, such as aircrafts, rotorcrafts and aviation transports. Both metallic materials and composite materials are widely used and affected by fatigue damage. Huge uncertainties arise from material properties, measurement noise, imperfect models, future anticipated loads and environmental conditions. These uncertainties are critical issues for accurate remaining useful life (RUL) prediction for engineering structures in service. Probabilistic fatigue prognosis considering various uncertainties is of great importance for structural safety. The objective of this study is to develop probabilistic fatigue life prediction models for metallic materials and composite materials. A fatigue model based on crack growth analysis and equivalent initial flaw size concept is proposed for metallic materials. Following this, the developed model is extended to include structural geometry effects (notch effect), environmental effects (corroded specimens) and manufacturing effects (shot peening effects). Due to the inhomogeneity and anisotropy, the fatigue model suitable for metallic materials cannot be directly applied to composite materials. A composite fatigue model life prediction is proposed based on a mixed-mode delamination growth model and a stiffness degradation law. After the development of deterministic fatigue models of metallic and composite materials, a general probabilistic life prediction methodology is developed. The proposed methodology combines an efficient Inverse First-Order Reliability Method (IFORM) for the uncertainty propogation in fatigue life prediction. An equivalent stresstransformation has been developed to enhance the computational efficiency under realistic random amplitude loading. A systematical reliability-based maintenance optimization framework is proposed for fatigue risk management and mitigation of engineering structures.

Xiang, Yibing

321

Nanostructured Functional Inorganic Materials Templated by Natural Substances  

Microsoft Academic Search

\\u000a Naturally-produced sophisticated hierarchal structures and the astonishing properties of biological substances are difficult\\u000a to obtain artificially, even with the most technologically advanced synthetic methodologies. As the needs for the development\\u000a of advanced materials with improved performance characteristics become increasingly important, the potential of natural substances\\u000a for material design and fabrication is being actively explored. The combination of versatile synthetic chemical

Yuanqing Gu; Jianguo Huang

322

Nature: Self-Healing Polymers and Other Improved Materials  

NASA Astrophysics Data System (ADS)

We have chosen articles from recent issues of Nature that explore ways to mimic and improve materials and processes found in nature. Some of the work has progressed toward industrial applications (e.g. using biocatalysts for selective organic syntheses), whereas other approaches (e.g. designing self-healing material) are still in their infancy but show remarkable promise for future success.

Featured on the Cover

Heinhorst, Sabine; Cannon, Gordon

2002-01-01

323

Fabrication of Composite Material Using Gettou Fiber by Injection Molding  

NASA Astrophysics Data System (ADS)

This study investigated the mechanical properties of composite using gettou (shell ginger) fiber as reinforcement fabricated from injection molding. Gettou fiber is a natural fiber made from gettou, a subtropical plant that is largely abundant in Okinawa, Japan. We used the stem part of gettou plant and made the gettou fiber by crushing the stem. The composite using gettou fiber contributed to low shrinkage ratio, high bending strength and high flexural modulus. The mechanical strength of composite using long gettou fiber showed higher value than composite using short gettou fiber. Next, because gettou is particularly known for its anti-mold characteristic, we investigated the characteristic in gettou plastic composite. The composite was tested against two molds: aspergillius niger and penicillium funiculosum. The 60% gettou fiber plastic composite was found to satisfy the JISZ2801 criterion. Finally, in order to predict the flexural modulus of composite using gettou fiber by Halpin-Tsai equation, the tensile elastic modulus of single gettou fiber was measured. The tendency of the experimental results of composite using gettou fiber was in good agreement with Halpin-Tsai equation.

Setsuda, Roy; Fukumoto, Isao; Kanda, Yasuyuki

324

Optimization of internal damping in fiber reinforced composite materials  

SciTech Connect

This dissertation describes new, reliable, and fast impulse techniques for characterization of damping in fiber reinforced composite materials. Flexural and extensional vibration tests are used for determination of complex moduli of aligned discontinuous fiber composite, and off axis fiber composite specimens, respectively. The results from these tests are then compared with theoretical predictions from micromechanics models based on a single fiber. The analytical model is fitted to the experimental results by varying certain parameters that have uncertainties associated with them. It is shown that improved damping can be obtained with very low fiber aspect ratios, and that even better damping properties are possible with off-axis fibers. These results were obtained from tests done on three different fiber reinforced composite materials: graphite/epoxy, Kevlar/epoxy and boron/epoxy.

Suarez, S.A.

1985-01-01

325

Use of natural zeolite as a supplementary cementitious material  

Microsoft Academic Search

Natural zeolite, a type of frame-structured hydrated aluminosilicate mineral, is used abundantly as a type of natural pozzolanic material in some regions of the world. In this work, the effectiveness of a locally quarried zeolite in enhancing mechanical and durability properties of concrete is evaluated and is also compared with other pozzolanic admixtures. The experimental tests included three parts: In

Babak Ahmadi; Mohammad Shekarchi

2010-01-01

326

Theories and Conflict: The Origins of Natural Gas. Instructional Materials.  

ERIC Educational Resources Information Center

This unit explores a recent and controversial theory of the origin of much of the Earth's natural gas and oil. The materials provided will give students the opportunity to: (1) gain an understanding of science and what is involved in the acceptance or rejection of theories; (2) learn about fossil fuels, especially natural gas; (3) learn the…

Anderson, Susan

327

Simulation of composite material response under dynamic compressive loading  

SciTech Connect

Realistic computer prediction of high-velocity impact and penetration events involving composite materials requires a knowledge of the material behavior under large compressive stresses at high rates of deformation. As an aid to the development of constitutive models for composites under these conditions, methods for numerical simulation of the material response at the microstructural level are being developed. At present, the study is confined to glass fiber/epoxy composites. The technique uses a numerical model of a representative sample of the microstructure with randomly distributed fibers. By subjecting the boundary of this numerical sample to prescribed loading histories, a statistical interpretation allows prediction of the global material response. Because the events at the microstructural scale involve locally large deformation, and because of the constantly changing picture with regard to contact between the fibers, the Eulerian code CTH is used for these calculations. Certain aspects of material failure can also be investigated using this approach. The method allows the mechanical behavior of composite materials to be studied with fewer assumptions about constituent behavior and morphology than typically required in analytical efforts.

Silling, S.A.; Taylor, P.A.

1993-12-31

328

Material selection and grade optimization applied to aluminum matrix composites  

SciTech Connect

A general model for the optimal use of materials based on structural optimization is derived. The competitiveness of materials is assessed with merit parameters. The competition between materials (material selection optimization) and the role of the composition and microstructure for a given material (grade optimization) are analyzed. The model is applied to aluminum matrix composites. The influence of matrix material, amount of reinforcement, and value of weight savings is studied. Mechanical properties are analyzed with the aid of published experimental data and available models. The Tsai-Halpin model is used to represent the variation of the elastic modulus with the amount of reinforcement. For yield strength the modified shear lag model is applied. It can satisfactorily describe experimental data and the variation with reinforcement for high-strength matrix alloys. For aluminum alloys of medium and lower strength, the observed increase is larger than the predicted one. This can be explained by the help of more recently developed micromechanical models that take into account the changes in microstructure in the matrix. For structural parts, large values of weight savings are usually necessary to make the particulate-reinforced composites competitive with carbon steel or their parent aluminum alloys. In other applications, combinations of properties are important to make the composites competitive.

Eliasson, J.; Sandstroem, R. [Royal Inst. of Tech., Stockholm (Sweden). Materials Science and Engineering

1995-06-01

329

Material selection and grade optimization applied to aluminum matrix composites  

NASA Astrophysics Data System (ADS)

A general model for the optimal use of materials based on structural optimization is derived. The competitiveness of materials is assessed with merit parameters. The competition between materials ( material selection optimization) and the role of the composition and microstructure for a given material ( grade optimization) are analyzed. The model is applied to aluminum matrix composites. The influence of matrix material, amount of reinforcement, and value of weight savings is studied. Mechanical properties are analyzed with the aid of published experimental data and available models. The Tsai-Halpin model is used to represent the variation of the elastic modulus with the amount of reinforcement. For yield strength the modified shear lag model is applied. It can satisfactorily describe experimental data and the variation with reinforcement for high-strength matrix alloys. For aluminum alloys of medium and lower strength, the observed increase is larger than the predicted one. This can be explained with the help of more recently developed micromechanical models that take into account the changes in microstructure in the matrix. For structural parts, large values of weight savings are usually necessary to make the particulate-reinforced composites competitive with carbon steel or their parent aluminum alloys. In other applications, combinations of properties are important to make the composites competitive.

Eliasson, J.; Sandström, R.

1995-06-01

330

Preparation and antimicrobial ability of natural proous antibacterial materials  

Microsoft Academic Search

The liquid ion exchange method, solid salt melt method and dry-wet circulation method were used to prepare natural porous\\u000a antimicrobial materials with natural minerals, such as zeolite, spilite, palygorskite and montmorillonite, respectively. Atomic\\u000a absorption spectrum and X-ray diffraction analysis were carried out to investigate the effects of Ag+, Cu2+ and Zn2+ on antimicrobial abilities of natural porous minerals, and the

Fa-qin Dong; Guo-wu Li; Zhi-gang Sun; Gang Shen; Qi-ming Feng; Qun-wei Dai

2005-01-01

331

Grained composite materials prepared by combustion synthesis under mechanical pressure  

DOEpatents

Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

Dunmead, Stephen D. (Davis, CA); Holt, Joseph B. (San Jose, CA); Kingman, Donald D. (Danville, CA); Munir, Zuhair A. (Davis, CA)

1990-01-01

332

High-specific-energy composite-material flywheel. Final report  

SciTech Connect

A flywheel rotor has been designed and fabricated to demonstrate energy densities ranging from 50.6 watt-hour/kg (23 watt-hour/lb) to 88 watt-hour/kg (40 watt-hour/lb). The design is composed of a multiring rim made of S-2 glass/epoxy and Kevlar/epoxy composite materials, mounted on a four-spoke aluminum and graphite/epoxy composite hub. Ten flywheel rotors were produced for test.

Not Available

1983-03-29

333

Radiopacity of experimental composite resins containing radiopaque materials.  

PubMed

This study aimed to investigate the relationship between the radiopacity of an experimental light-cured composite resin and the amount and type of its radiopaque material: Ti, SrCO3, ZrO2, BaSO4, or Bi2O3. Radiopacity of each material was evaluated in terms of aluminum equivalent thickness using an aluminum step wedge. Then, the half-value layer thickness of the experimental composite resin, which had an aluminium equivalent thickness of 1 mm, was evaluated. It was found that the effects of elemental composition were not identical when evaluated in terms of aluminum equivalent thickness and by half-value layer. Nevertheless, both measurement methods indicated that radiopacity increased with increase in radiopaque material content as well as increase in atomic number of the element. PMID:16279720

Aoyagi, Yujin; Takahashi, Hidekazu; Iwasaki, Naohiko; Honda, Ei-ichi; Kurabayashi, Toru

2005-09-01

334

Hot extruded carbon nanotube reinforced aluminum matrix composite materials.  

PubMed

Carbon nanotube (CNT) reinforced aluminum (Al) matrix composite materials were successfully fabricated by mechanical ball milling followed by powder hot extrusion processes. Microstructural analysis revealed that the CNTs were well dispersed at the boundaries and were aligned with the extrusion direction in the composites obtained. Although only a small quantity of CNTs were added to the composite (1 vol%), the Vickers hardness and the tensile strength were significantly enhanced, with an up to three-fold increase relative to that of pure Al. From the fractography of the extruded Al-CNT composite, several shapes were observed in the fracture surface, and this unique morphology is discussed based on the strengthening mechanism. The damage in the CNTs was investigated with Raman spectroscopy. However, the Al-CNT composite materials were not only strengthened by the addition of CNTs but also enhanced by several synergistic effects. The nanoindentation stress-strain curve was successfully constructed by setting the effective zero-load and zero-displacement points and was compared with the tensile stress-strain curve. The yield strengths of the Al-CNT composites from the nanoindentation and tensile tests were compared and discussed. We believe that the yield strength can be predicted using a simple nanoindentation stress/strain curve and that this method will be useful for materials that are difficult to machine, such as complex ceramics. PMID:23011263

Kwon, Hansang; Leparoux, Marc

2012-09-26

335

Hot extruded carbon nanotube reinforced aluminum matrix composite materials  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT) reinforced aluminum (Al) matrix composite materials were successfully fabricated by mechanical ball milling followed by powder hot extrusion processes. Microstructural analysis revealed that the CNTs were well dispersed at the boundaries and were aligned with the extrusion direction in the composites obtained. Although only a small quantity of CNTs were added to the composite (1 vol%), the Vickers hardness and the tensile strength were significantly enhanced, with an up to three-fold increase relative to that of pure Al. From the fractography of the extruded Al-CNT composite, several shapes were observed in the fracture surface, and this unique morphology is discussed based on the strengthening mechanism. The damage in the CNTs was investigated with Raman spectroscopy. However, the Al-CNT composite materials were not only strengthened by the addition of CNTs but also enhanced by several synergistic effects. The nanoindentation stress-strain curve was successfully constructed by setting the effective zero-load and zero-displacement points and was compared with the tensile stress-strain curve. The yield strengths of the Al-CNT composites from the nanoindentation and tensile tests were compared and discussed. We believe that the yield strength can be predicted using a simple nanoindentation stress/strain curve and that this method will be useful for materials that are difficult to machine, such as complex ceramics.

Kwon, Hansang; Leparoux, Marc

2012-10-01

336

Thermally mediated multiferroic composites for the magnetoelectric materials  

NASA Astrophysics Data System (ADS)

A magnetoelectric (ME) composite through thermal mediation is presented, which is different from the traditional strain/stress mediated ME composites. The ME laminate uses the large magnetocaloric effect, that is, a temperature change induced in the ferromagnetic Gd crystal by a magnetic field, and a large pyroelectric response in the relaxor ferroelectric polymer. Consequently, a simple laminate composite can produce a ME response ~0.5 V/(cm Oe). The ME coefficient was further enhanced to ~0.9 V/(cm Oe) by exploiting the magnetic flux concentration effect. The approach opens up an avenue in developing ME materials for broad range of applications.

Lu, S. G.; Fang, Z.; Furman, E.; Wang, Y.; Zhang, Q. M.; Mudryk, Y.; Gschneidner, K. A.; Pecharsky, V. K.; Nan, C. W.

2010-03-01

337

Effective thermal conductivity of a thin, randomly oriented composite material  

SciTech Connect

The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thicknesses. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relative low thermal conductivity. The results indicate that, below some threshold thickness, the composite thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between the filler and matrix thermal conductivities.

Phelan, P.E. [Arizona State Univ., Tempe, AZ (United States). Dept. of Mechanical and Aerospace Engineering; Niemann, R.C. [Argonne National Lab., IL (United States). Energy Technology Div.

1997-10-01

338

A thermodynamical constitutive model for shape memory materials. Part II. The SMA composite material  

Microsoft Academic Search

The phenomenological SMA equations developed in Part I are used in this second paper to derive the free energy and dissipation of a SMA composite material. The derivation consists of solving a boundary value problem formulated over a mesoscale representative volume element, followed by an averaging procedure to obtain the macroscopic composite constitutive equations. Explicit equations are derived for the

James G. Boyd; Dimitris C. Lagoudas

1996-01-01

339

Nondestructive inspection and evaluation of composite-material flywheels  

SciTech Connect

Several composite panels and flywheel designs were evaluated in support of the Mechanical Energy Storage Technology (MEST) project. Conventional nondestructive evaluation (NDE) technology was used on the panels and flywheels. All flywheels and panels were radiographed and, where practical, were also inspected using ultrasonic techniques. The results provided information about the structural features of flywheels and materials. This information is useful for the quality control of fabrication procedures. The detection of apparent flaws in fabrication cannot be related to the ultimate strength until failure mechanisms in composite materials have been fully defined. Therefore, the location of detected flaws should be recorded for later comparison with dynamic and destructive evaluations.

Boyd, D.M.; Maxfield, B.W.; Kulkarni, S.V.; Schwarber, A.J.

1982-02-24

340

Self-healing bentonite sheet material composite drainage structure  

SciTech Connect

A composite drainage structure capable of directing water longitudinally away from a potential area of water flow and incapable of transverse water penetration is described comprising: drainage means for receiving water and channeling the water to a predetermined area; channel means disposed between the first and second sheet materials of the drainage means for channeling water longitudinal within the drainage means to the predetermined area; and a cohesive layer of a water-swellable clay composition secured to the water-impermeable layer of sheet material.

Harriett, T.D.

1988-03-29

341

NDE of composite materials using ultrasonic oblique insonification  

SciTech Connect

The analysis of reflected ultrasonic waves induced by oblique insonification of composite materials is increasingly recognized as a powerful tool in providing information about defects and material properties. The theoretical modeling of the wave behavior for tone-burst and pulses has been very successful in accurately corroborating the experimental results. The data repeatability and accuracy make oblique insonification methods easy to standardize for practical applications. Recent theoretical and experimental results and the progress in using frequency- and time-domain data are discussed with an emphasis on the application to graphite/epoxy composites.

Bar-Cohen, Y. (California Inst. of Tech., Pasadena, CA (United States). Jet Propulsion Lab.); Mal, A.K.; Lih, Shyh-Shiuh (Univ. of California, Los Angeles, CA (United States). Mechanical, Aerospace, and Nuclear Engineering Dept.)

1993-11-01

342

Silicon carbide composites as fusion power reactor structural materials  

NASA Astrophysics Data System (ADS)

Silicon carbide was first proposed as a low activation fusion reactor material in the mid 1970s. However, serious development of this material did not begin until the early 1990s, driven by the emergence of composite materials that provided enhanced toughness and an implied ability to use these typically brittle materials in engineering application. In the decades that followed, SiC composite system was successfully transformed from a poorly performing curiosity into a radiation stable material of sufficient maturity to be considered for near term nuclear and non-nuclear systems. In this paper the recent progress in the understanding and of basic phenomenon related to the use of SiC and SiC composite in fusion applications will be presented. This work includes both fundamental radiation effects in SiC and engineering issues such as joining and general materials properties. Additionally, this paper will briefly discuss the technological gaps remaining for the practical application of this material system in fusion power devices such as DEMO and beyond.

Snead, L. L.; Nozawa, T.; Ferraris, M.; Katoh, Y.; Shinavski, R.; Sawan, M.

2011-10-01

343

Development of biomimetical composite prosthetic ligaments using mechanically dissimilar materials  

Microsoft Academic Search

Using high performance textile materials and novel designs, structures were developed which have the potential for mimicking the properties of natural anterior cruciate ligaments (ACLs). Six tubular braided structures capable of withstanding the loads encountered by ACL, were built. Elastomeric materials were incorporated as cores in order to give the devices the ability to recover from strains. Mechanical and viscoelastic

F. T. Moutos; B. S. Gupta

1999-01-01

344

Modular design in natural and biomimetic soft materials.  

PubMed

Under eons of evolutionary and environmental pressure, biological systems have developed strong and lightweight peptide-based polymeric materials by using the 20 naturally occurring amino acids as principal monomeric units. These materials outperform their man-made counterparts in the following ways: 1) multifunctionality/tunability, 2) adaptability/stimuli-responsiveness, 3) synthesis and processing under ambient and aqueous conditions, and 4) recyclability and biodegradability. The universal design strategy that affords these advanced properties involves "bottom-up" synthesis and modular, hierarchical organization both within and across multiple length-scales. The field of "biomimicry"-elucidating and co-opting nature's basic material design principles and molecular building blocks-is rapidly evolving. This Review describes what has been discovered about the structure and molecular mechanisms of natural polymeric materials, as well as the progress towards synthetic "mimics" of these remarkable systems. PMID:21898722

Kushner, Aaron M; Guan, Zhibin

2011-09-05

345

DNA hybridization to compare species compositions of natural bacterioplankton assemblages.  

PubMed Central

Little is known about the species composition and variability of natural bacterial communities, mostly because conventional identification requires pure cultures, but less than 1% of active natural bacteria are cultivable. This problem was circumvented by comparing species compositions via hybridization of total DNA of natural bacterioplankton communities for the estimation of the fraction of DNA in common between two samples (similarity). DNA probes that were labeled with 35S by nick translation were hybridized to filter-bound DNA in a reciprocal fashion; similarities (in percent) were calculated by normalizing the values to self-hybridizations. In tests with DNA mixtures of pure cultures, the experimentally observed similarities agreed with expectations. However, reciprocal similarities (probe and target reversed) were often asymmetric, unlike those of DNA from single strains. This was due to the relative complexity and G + C content of DNA, which provided a means to interpret the asymmetry that was occasionally observed in natural samples. Natural bacteria were collected by filtration from Long Island Sound (LIS), N.Y., the Caribbean and Sargasso seas, and a coral reef lagoon near Bermuda. The samples showed similarities of less than 10 to 95%. The LIS and Sargasso and Caribbean sea samples were 20 to 50% similar to each other. The coral reef sample was less than 10% similar to the others, indicating its unique composition. Seasonality was also observed; an LIS sample obtained in the autumn was 40% similar to two LIS samples obtained in the summer; these latter two samples were 95% similar. We concluded that total DNA hybridization is a rapid, simple, and unbiased method for investigating the variation of bacterioplankton species composition over time and space, avoiding the need of culturing.

Lee, S; Fuhrman, J A

1990-01-01

346

Negotiating through nature: The resistant materiality and materiality of resistance in Bolivia’s natural gas sector  

Microsoft Academic Search

Over the past two decades, the natural gas of Bolivia has been a point of international interest and internal contention. Materially and discursively using Bolivia’s natural gas to express their demands, transnational energy firms, the Bolivian state, and Bolivia’s social movements have made the country’s natural gas into an object of profit and protest. In this paper, I examine how

Brent Z. Kaup

2008-01-01

347

Contact acoustic nonlinearity phenomenon caused by the acoustic wave propagating in the composite material  

Microsoft Academic Search

Due to the massive applications of multilayered composite materials (for example carbon fiber material, glass fiber material etc.) in material industry, aviation industry, medical enterprise and other consumer industries, it becomes an important work to carry on the non-destructive evaluation to the long-term characteristic and the security of the composite materials in use. The reliability of a composite material is

Jian-jun Chen; De Zhang; Yi-wei Mao

2008-01-01

348

A polymethacrylate-silica composite material for dental implants.  

PubMed

A study has been carried out on the structure and surface texture of a new dental implant material composed of silica microspheres (3 or 5 wt%) and poly(methyl methacrylate). A recently developed composite material composed of vitreous carbon microballoons and poly(methyl methacrylate) has proven highly successful in clinical use, but the black color presents aesthetic problems at the gingival margin. The new material was developed in order to reproduce the many desirable qualities of the vitreous carbon-polymethacrylate composite, while omitting the black color. Square wafers (10 mm X 10 mm X1 mm) were studied, with the surface sandblasted in half of the specimens. Light microscopy revealed an even spacing of spherical configurations throughout the material. Scanning electron microscope studies revealed a finely porous surface with many large craters in the sandblasted specimens. PMID:201644

Hodosh, M; Shklar, G

1977-11-01

349

Inhibition of catalytic oxidation of carbon\\/carbon composite materials  

Microsoft Academic Search

An investigation coupling experimental efforts with computational chemistry analysis was conducted to study the inhibition effects of phosphorous or boron on the oxidation of carbon\\/carbon composite materials catalyzed by potassium or calcium acetate (KAC or CaAC). Commercial aircraft brakes were used, which are exposed during use to K- or Ca-containing runway deicing agents. The reactivity of inhibitor-doped carbon materials was

Xianxian Wu

2002-01-01

350

Composite materials of nichrome with molybdenum and with tungsten  

Microsoft Academic Search

1.Hot isothermal pressing of nickel-chromium composites reinforced with refractory filaments makes it possible to regulate the parameters of the process and ensures obtaining a dense material with a given distribution of filament and high volume percentage of the filament.In combination with subsequent rolling, this method makes it possible to manufacture dense materials strengthened with grids.2.A white nonetching zone is formed

F. P. Banas; V. V. Gaiduk; B. S. Natapov; B. V. Aleksandrov; L. N. Efimenko

1971-01-01

351

Application of silcomp composite materials to turbine systems  

Microsoft Academic Search

A Si\\/SiC family of high temperature composite materials is being developed which, in some respects, resembles the related reaction bonded SiC materials in terms of its corrosion resistance, temperature limits, etc., but differs in the ability to tailor its mechanical properties over a fairly wide range. Two iterations of prototype turbine combustor components have been designed and fabricated from it

Hillig

1978-01-01

352

An experimental and finite element analysis of the static deformation of natural fiber-reinforced composite beam  

Microsoft Academic Search

This paper describes the application of the shadow moiré method for direct measurement of the whole-field deformation of a cantilever beam, made from natural fiber-reinforced composite (NRFC) material, under static loading and comparison of the experimental results with those predicted using finite element analysis (FEA). The material properties required in the FEA were obtained by calculating the mean of the

J. H. Lim; M. M. Ratnam; H. P. S. Abdul Khalil

2003-01-01

353

The Behaviour of Naturally Debonded Composites Due to Bending Using a Meso-Level Model  

NASA Astrophysics Data System (ADS)

Numerical simulations and analytical models are increasingly being sought for the design and behaviour prediction of composite materials. The use of high-performance composite materials is growing in both civilian and defence related applications. With this growth comes the necessity to understand and predict how these new materials will behave under their exposed environments. In this study, the displacement behaviour of naturally debonded composites under out-of-plane bending conditions has been investigated. An analytical approach has been developed to predict the displacement response behaviour. The analytical model supports multi-layered composites with full and partial delaminations. The model can be used to extract bulk effective material properties in which can be represented, later, as an ESL (Equivalent Single Layer). The friction between each of the layers is included in the analytical model and is shown to have distinct behaviour for these types of composites. Acceptable agreement was observed between the model predictions, the ANSYS finite element model, and the experiments.

Lord, C. E.; Rongong, J. A.; Hodzic, A.

2012-06-01

354

The histochemical nature of homogeneous amorphous materials in odontogenic epithelial tumors.  

PubMed

The homogeneous acellular materials in the adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, and calcifying odontogenic cyst were examined histochemically for specific staining of amino acids and protein groups. These materials gave a positive reaction for periodic acid-Sciff (PAS), alloxan-Schiff, and dinitrofluorobenzene-H-acid and low reaction for alcian blue, dimethylaminobenzaldehyde (method for tryptophan) and the Morel-Sisley diazotization method. They appear to have approximately the same composition as enamel matrix and are not amyloid in nature. The materials may be synthesized products from neoplastic epithelium that may originate from enamel organs. PMID:6153217

Mori, M; Makino, M; Imai, K

1980-02-01

355

Alternative processing methods for tungsten-base composite materials  

SciTech Connect

Tungsten composite materials contain large amounts of tungsten distributed in a continuous matrix phase. Current commercial materials include the tungsten-nickel-iron with cobalt replacing some or all of the iron, and also tungsten-copper materials. Typically, these are fabricated by liquid-phase sintering of blended powders. Liquid-phase sintering offers the advantages of low processing costs, established technology, and generally attractive mechanical properties. However, liquid-phase sintering is restricted to a very limited number of matrix alloying elements and a limited range of tungsten and alloying compositions. In the past few years, there has been interest in a wider range of matrix materials that offer the potential for superior composite properties. These must be processed by solid-state processes and at sufficiently low temperatures to avoid undesired reactions between the tungsten and the matrix phase. These processes, in order of decreasing process temperature requirements, include hot-isostatic pressing (HIPing), hot extrusion, and dynamic compaction. The HIPing and hot extrusion processes have also been used to improve mechanical properties of conventional liquid-phase-sintered materials. Results of laboratory-scale investigations of solid-state consolidation of a variety of matrix materials, including titanium, hafnium, nickel aluminide, and steels are reviewed. The potential advantages and disadvantages of each of the possible alternative consolidation processes are identified. Postconsolidation processing to control microstructure and macrostructure is discussed, including novel methods of controlling microstructure alignment.

Ohriner, E.K.; Sikka, V.K.

1995-12-31

356

Airborne ultrasonic inspection in carbon/carbon composite materials  

NASA Astrophysics Data System (ADS)

In this work, a carbon/carbon (C/C) composite material was nondestructively characterized with non-contact ultrasonic methods using automated acquisition scanner as well as contact ultrasonic measurement because (C/C) composite materials have obvious high price over conventional materials. Because of permeation of coupling medium such as water, it is desirable to perform contact-less nondestructive evaluation to assess material properties and part homogeneity. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. Especially ultrasonic images and velocities for C/C composite disk brake was measured and found to be consistent to some degree with the non-contact and contact ultrasonic measurement methods. Low frequency through-transmission scans based on both amplitude and time-of-flight of the ultrasonic pulse were used for mapping out the material property inhomogeneity. Measured results were compared with those obtained by the motorized system with using dry-coupling ultrasonics and through transmission method in immersion. Finally, results using a proposed peak-delay measurement method well corresponded to ultrasonic velocities of the pulse overlap method.

Yang, In-Young; Kim, Young-Hun; Park, Je-Woong; Hsu, David K.; Song, Song-Jin; Cho, Hyun-Jun; Kim, Sun-Kyu; Im, Kwang-Hee

2007-10-01

357

LOW-COST COMPOSITES IN VEHICLE MANUFACTURE - Natural-fiber-reinforced polymer composites in automotive applications.  

SciTech Connect

In the last decade, natural fiber composites have experienced rapid growth in the European automotive market, and this trend appears to be global in scale, provided the cost and performance is justified against competing technologies. However, mass reduction, recyclability, and performance requirements can be met today by competing systems such as injection-molded unreinforced thermoplastics; natural fiber composites will continue to expand their role in automotive applications only if such technical challenges as moisture stability, fiber-polymer interface compatibility, and consistent, repeatable fiber sources are available to supply automotive manufacturers. Efforts underway by Tier I and II automotive suppliers to explore hybrid glass-natural fiber systems, as well as applications that exploit such capabilities as natural fiber sound dampening characteristics, could very well have far-reaching effects. In addition, the current development underway of bio-based resins such as Polyhydroxyalkanoate (PHA) biodegradable polyesters and bio-based polyols could provide fully bio-based composite options to future automotive designers. In short, the development of the natural fiber composite market would make a positive impact on farmers and small business owners on a global scale, reduce US reliance on foreign oil, improve environmental quality through the development of a sustainable resource supply chain, and achieve a better CO2 balance over the vehicle?s lifetime with near-zero net greenhouse gas emissions.

Holbery, Jim; Houston, Dan

2006-11-01

358

Compendium of Material Composition Data for Radiation Transport Modeling  

SciTech Connect

Computational modeling of radiation transport problems including homeland security, radiation shielding and protection, and criticality safety all depend upon material definitions. This document has been created to serve two purposes: 1) to provide a quick reference of material compositions for analysts and 2) a standardized reference to reduce the differences between results from two independent analysts. Analysts are always encountering a variety of materials for which elemental definitions are not readily available or densities are not defined. This document provides a location where unique or hard to define materials will be located to reduce duplication in research for modeling purposes. Additionally, having a common set of material definitions helps to standardize modeling across PNNL and provide two separate researchers the ability to compare different modeling results from a common materials basis.

Williams, Ralph G.; Gesh, Christopher J.; Pagh, Richard T.

2006-10-31

359

Fractography of modern engineering materials: Composites and metals, Second volume  

SciTech Connect

This book contains the manuscripts of eleven papers that were presented at the Second Symposium on Fractography of Modern Engineering Materials held in May 1992. The numerous advances in materials science in the six year period following the First Symposium dictated this second meeting. Not only had new materials been developed in the intervening years, but understanding of older materials had also progressed. Similarly, advances in the technology and the techniques of fractography had occurred. The objective of the symposium was to extend the colloquy on fractography to include these many advances. The paper may be divided into three sections: Unique Fractographic Techniques; Metallic Materials; Polymeric and Composite Materials. The section titles reflect the diversity of materials discussed in the meeting. The range of materials included cross-linked polyethylene, AISI 52100 steel, 2024 aluminum, and a variety of organic and metal matrix fibrous composites. The case studies presented also covered a wide range. They included failure investigations of an antenna used in deep space exploration and chemical storage tanks. Advances in the techniques of fractography were also reflected in a number of presentations; quantitative techniques and expert systems were also subjects of presentations. A short precis of each paper is included here to assist the readers in identifying works of particular interest.

Masters, J.E.; Gilbertson, L.N. (eds.)

1993-01-01

360

The Absolute Isotopic Composition of Zn in Terrestrial Materials Determined Using Double Spike Thermal Ionization Mass Spectrometry  

Microsoft Academic Search

Although long suspected to be widespread in nature, until recently, little was known about the extent of the variation of the isotopic composition, or isotopic fractionation, of Zn in natural materials. During the last decade an increasing number of high precision Zn isotopic fractionation data have been reported using MC- ICP-MS (MARECHAL et al., 1999; PETIT et al., 2008; PICHAT

O. Y. Ghidan; R. D. Loss

2008-01-01

361

Transverse thermal conductance of thermosetting composite materials during their cure  

SciTech Connect

The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4/3501-6 graphite/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh was modified to account for the possible effects of a fiber/resin contact resistance and for the ransversely anisotropic behavior of the composites' thermal conductivity. A model was derived that accounts for the effect of resin heat generation on the measured thermal conductivity of an uncured thermosetting composite. These models were experimentally verified using a guarded hot plate apparatus to measure the thermal conductivity of the graphite/epoxy laminates as a function of independent cure variables. 29 refs.

Farmer, J.D.; Covert, E.E.

1993-01-01

362

Transverse thermal conductance of thermosetting composite materials during their cure  

SciTech Connect

The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4/3501-6 graphite/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh, was modified to account for the possible effects of a fiber/resin contact resistance and for the transversely anisotropic behavior of the composites' thermal conductivity. A model was derived that accounts for the effect of resin heat generation on the measured thermal conductivity of an uncured thermosetting composite. These models were investigated experimentally using a guarded hot plate apparatus to measure the thermal conductivity of the graphite/epoxy laminates as a function of independent cure variables. Good agreement was found between the models and the experimental data. 80 refs.

Farmer, J.D.; Covert, E.E. (Massachusetts Inst. of Technology, Cambridge, MA (United States))

1994-04-01

363

Ptah-socar fuel-cooled composite materials structure  

NASA Astrophysics Data System (ADS)

One of the key points for the development of dual-mode ramjets operating up to Mach 8 or more is the mastery of fuel-cooled composite materials structures, which are needed, at least, for the combustion chamber. MBDA France and EADS ST have been working on the development of a particular technology for such structures taking advantage of the background of MBDA France in the field of dual-mode ramjet and fuel-cooled structures and of ASTRIUM-EADS ST in the field of high-temperature composite materials. They have developed an innovative technology for advanced monobloc cooled C/C/SiC structures. The paper gives an updated status of the development of Paroi Tissée Application Hypersonique - Simple Operational Composite for Advanced Ramjet (PTAH-SOCAR) technology, including test results, and presents some results obtained during system and demonstrator studies.

Bouchez, M.; Beyer, S.

2009-09-01

364

Intermetallic and titanium matrix composite materials for hypersonic applications  

Microsoft Academic Search

As part of the French Program of Research and Technology for Advanced Hypersonic Propulsion (PREPHA) which was launched in 1992 between Aerospatiale, Dassault Aviation, ONERA, SNECMA and SEP, an important work is specially devoted to the development of titanium and intermetallic composite materials for large airframe structures. At Dassault Aviation, starting from a long experience in Superplastic Forming - Diffusion

B. Berton; G. Surdon; C. Colin

1995-01-01

365

Vibrations of Stiffened Composite Panels With Smart Materials  

Microsoft Academic Search

The feasibility of using electrorheological (ER) fluids and self-sensing piezoelectric (PZT) actua- tors to control structural vibrations of stiffened composite panels subjected to wide-band random inputs is investigated. A collocated velocity feedback control mechanism is integrated using piezoelectric materials as sensors and actuators. Control of structural dynamic characteristics is introduced by elec- trorheological fluids located in the stiffeners. The transfer

Kevin C. Poulin; Rimas Vaicaitis

2004-01-01

366

Polymeric composite photorefractive materials for nonlinear optical applications  

NASA Astrophysics Data System (ADS)

Polymeric composite materials constitute a new and very promising class of photorefractive materials. In the design of polymeric photorefractive materials we use multicomponent composites in which necessary functionalities can be independently optimized. The investigated composites consisted of charge transporting polymeric matrix, and optically second-order active molecules. Two different photosensitizers were used to vary the wavelength response. Photorefractive properties of these materials were investigated using erasable volume holography in a non-degenerate four-wave mixing geometry and two-beam coupling techniques. A previously developed model of space-charge field grating formation in photoconductive polymers was used to explain the field dependence of four-wave mixing diffraction efficiency. The model takes into account the field dependence of charge photogeneration quantum yield, carrier field mobility, and electro-optic coefficient. Necessary information about these parameters was obtained from the results of photoconductivity and electro-optic modulation experiments. Special attention was focused on the kinetics of photorefractive response in the composite for optical signal processing and optical storage. It was found that a very effective switching of diffraction efficiency induced by dc electric field occurs in this system. Also, the results of kinetic studies of the index grating writing and its subsequent light-induced erasure, as well as a demonstration of the holographic image recording and retrieval, are reported.

Prasad, Paras N.; Orczyk, Maciek E.; Zieba, Jaroslaw W.; Burzynski, Ryszard; Zhang, Yue; Ghosal, Saswati; Casstevens, Martin K.

1994-05-01

367

Method and Apparatus for Gripping Uniaxial Fibrous Composite Materials.  

National Technical Information Service (NTIS)

A strip specimen is cut from a unidirectional strong, brittle fiber composite material, and the surfaces of both ends of the specimen are grit-blasted. The specimen is then placed between metal load transfer members having grit-blasted surfaces. Sufficien...

J. D. Whittenberger F. I. Hurwitz

1982-01-01

368

Ultrasonic inspection of impact induced damage in polymeric composite materials  

Microsoft Academic Search

An account is given of current performance capabilities in the ultrasonic inspection of graphite-epoxy composite materials of both simple laminate and sandwich type. Attention is given to damage types ranging from barely-visible impact effects to complete destruction. These ultrasonic inspection procedures have been implemented in the case of certification tests for the EH 101 helicopter.

R. Pezzoni; L. Merletti; G. Battagin; R. Denis

1992-01-01

369

Thermophysical properties of epoxy composite materials at low temperatures  

Microsoft Academic Search

The thermal conductivity, thermal diffusivity and specific heat of epoxy composite materials were investigated from 5 to 400 K. Experimental results of thermal expansion measurements in the temperature range 77–380 K are also presented. The spectrum of relaxation transitions is obtained by two independent methods; calorimetric and dilatometric.

I. E. Evseeva; S. A. Tanaeva

1995-01-01

370

Adsorbent new materials and composites produced in a single step  

Microsoft Academic Search

The aim of this work is the production and preliminary characterization of adsorbent new materials useful for sensor development. A new plasma chamber was simulated and designed in order to obtain multiple layers and\\/or composites in a single step. Plasma deposited organic fluorocompound and hexamethyldisilazane (HMDS) thin films were produced and tested as adsorbent layers. Chemical characterization used ellipsometry, Raman,

R. R. Lima; R. A. M. Carvalho; A. T. Carvalho; E. W. Simões; M. L. P. da Silva

2009-01-01

371

Thermal Expansion Coefficients of Composite Materials Based on Energy Principles  

Microsoft Academic Search

Bounds on effective thermal expansion coefficients of isotropic and anisotropic composite materials consisting of isotropic phases are derived by employing extremum principles of thermoelasticity. Inequalities between certain approximate and exact forms of the potential and complementary energy functionals are first estab lished. These inequalities are then used in conjunction with a new method for minimizing the difference between upper and

R. A. Schapery

1968-01-01

372

Damage evolution monitoring in unidirectional graphite\\/epoxy composite materials  

Microsoft Academic Search

Possible solutions to the difficulties associated with life prediction efforts in unidirectional graphite\\/epoxy composite laminates are suggested. Specimens were fatigue cycled at five different load levels to characterize the fatigue behavior as well as the scatter in the data for this material system. Based on S-N data for this system, the mean life of samples at each load level could

A. Razvan; M. Elahi; K. L. Reifsnider; C. Gaylord

1991-01-01

373

Multiscale Damage Modeling for Composite Materials: Theory and Computational Framework  

Microsoft Academic Search

A nonlocal multiscale continuum damage model is developed for brittle composite materials. A triple-scale asymptotic analysis is generalized to account for the damage phenomena occur- ring at micro-, meso- and macro- scales. A closed form expressions relating microscopic, mesoscopic and overall strains and damage is derived. The damage evolution is stated on the smallest scale of interest and nonlocal weighted

Jacob Fish; Qing Yu

374

Tungsten filament as reinforcement for heat resistant composite materials  

Microsoft Academic Search

Fine tungsten filament is a promising reinforcement for composite materials. This is due to the good properties of alloys based on tungsten - high recrystallizatio n temperature, high strength and modulus of elasticity in a fairly wide temperature range, and, particularly valuable, deformability of a continuous filament with a diameter from a few microns to several millimeters. Thin filaments are

N. M. Fonshtein; G. N. Tikhomirova; V. F. Kotov; V. I. Shvarts

1971-01-01

375

Studies of Tension Test Specimens for Composite Material Testing.  

National Technical Information Service (NTIS)

This report covers stress analysis and experimental studies of four types of tension specimens designed for testing composite materials. Two ASTM specimen types (D3039 tab-ended and D638 dogbone) are considered, along with the bowtie (flat bar with linear...

B. S. Parker D. W. Oplinger K. R. Gandhi

1982-01-01

376

Fatigue life prediction and failure mechanisms of composite materials  

Microsoft Academic Search

Fatigue life prediction and failure mechanisms of composite materials are studied based on the fatigue modulus concept and experimental results. Single-stress level fatigue life is predicted using generalized fatigue modulus degradation model and resultant strain failure criterion. Cumulative damage models defined by fatigue modulus and resultant strains are derived as functions of fatigue cycle and applied stress. This approach can

K. S. Han; W. Hwang

1992-01-01

377

OVERVIEW OF RESEARCH ON COMPOSITE MATERIAL IMPACT BEHAVIOR  

Microsoft Academic Search

Impact resistance of composite materials is an important area of research. Fiber reinforced polymer structures typically respond very poorly to transverse impact events. In addition uncertainties about the dominant mechanisms of damage make it difficult to ascertain the effect of an impact event on the performance of a FRP structure. Compounding these considerations is the fact that, in some cases,

Kurt Henkhaus; Guillermo Ramirez

378

Design And Formability Of A New Composite Material  

NASA Astrophysics Data System (ADS)

Composite materials with metallic cover sheets have been established based on their low weight potential in industrial applications. Further requirements such as high stiffness of component, vibration damping and formability today are only partially met by these composites. For that reason, in current research work, great efforts are being made to develop materials which can be adapted to their later use and load in terms of improving noise, vibration and harshness. Thus, greater stiffness of component structure with a simultaneous reduction of weight can be achieved. This article presents a new composite material which consists of a plane sheet, a thin intermediate damping-layer and a sheet with formed elements to increase stiffness of component such as beads. The plane side can be used as the visible part side. The shape elements increase strength due to work hardening and can be used as design or functional elements. Thus, this composite material results in several advantages within the single layers. Possible flexibility in component design enables new semi-finished or tailored components.

Bolay, C.; Liewald, M.

2011-05-01

379

High Stiffness Natural Fiber?Reinforced Hybrid Polypropylene Composites  

Microsoft Academic Search

Natural fibers are potentially a high?performance non?abrasive reinforcing fiber source. In this study, pulp fibers [including bleached Kraft pulp (BKP) and thermomechanical pulp (TMP)], hemp, flax, and wood flour were used for reinforcing in polypropylene (PP) composite. The results show that pulp fibers, in particular, TMP?reinforced PP has the highest tensile strength, possibly because pulp fibers were subjected to less

Haijun Li; Mohini M. Sain

2003-01-01

380

Electromagnetic Shielding of Oriented Carbon Fiber Composite Materials  

NASA Astrophysics Data System (ADS)

The paper analyses the electromagnetic shielding measurements of carbon fiber composite structure. In particular the shielding effectiveness is measured applying the nested reverberation chamber method in the frequency range of 3.5 GHz - 8.5 GHz. This method ensure a realistic electromagnetic excitation of the sample under test characterized by a random polarization and incoming direction. The paper also describes the material manufacturing procedure and gives important details about the sample mounting technique. Three material samples are considered which differ in carbon fiber orientation and stratification. Obtained results highlight the capability of such materials to behave as high-performance shields in the microwave region.

Micheli, D.; Laurenzi, S.; Mariani Primiani, V.; Moglie, F.; Gradoni, G.; Marchetti, M.

2012-05-01

381

Use of natural raw material for the production of photochromic glasses  

SciTech Connect

The authors investigated the possibility of using natural raw materials as replacements for soda and alumina for obtaining photochromic glasses and to determine their properties. Glasses of the sodium aluminoborosilicate system were studied. The characteristics of the batches and some of the properties of the glasses are given in a table. Sodium oxide was added to batches Nos. 1 and 2 as soda or borax. Composition Nos. 3, 4, and 5 were prepared using acid, basic, and neutral rocks by means of which the oxides of sodium and aluminum were added. The glasses were synthesized in SiC-heater furnaces. The differential thermal analysis of compositions Nos. 1 and 5 showed that the presence of natural materials leads to the formation of a liquid phase at lower temperatures which helps to intensify the processes of silicate- and glass-formation.

Kiyan, V.I.; Artamonova, M.V.; Solinov, V.F.

1986-07-01

382

A review on application of carbonaceous materials and carbon matrix composites for heat exchangers and heat sinks  

Microsoft Academic Search

Carbonaceous materials and carbon matrix composites (CAMCs) have potential to be used in heat exchangers and heat sinks for a number of thermal management applications related to HVAC&R systems, especially in high-temperature and corrosive environments. Recent developments in carbonaceous materials, such as new, natural graphite, carbon foam, carbon nanotubes, and CAMCs, open opportunities for new heat exchanger designs for compact

Q. Wang; X. H. Han; A. Sommers; C. T’ Joen; A. Jacobi

383

Bamboo fibre filled natural rubber composites: the effects of filler loading and bonding agent  

Microsoft Academic Search

Bamboo fibre reinforced natural rubber composites were prepared by incorporation of different loadings of bamboo fibre. Two series of composites were studied i.e. composites with and without the presence of a bonding agent. The curing characteristics of the composites were determined and the composites were vulcanized at 150°C using a hot press. The properties of the composites such as tensile

Hanafi Ismail; M. R. Edyham; B. Wirjosentono

2002-01-01

384

A VERSATILE ULTRASONIC MEASUREMENT SYSTEM FOR FLAW DETECTION AND MATERIAL PROPERTY CHARACTERIZATION IN COMPOSITE MATERIALS  

Microsoft Academic Search

There is an ever increasing interest in the use of polymer-matrix composite materials in high performance automotive, marine, and aerospace structures. Ultrasonic NDE is a particularly effective method of insuring that such materials are fit for their intended purpose. Specifically, ultrasonic methods are inherently appropriate for internal-flaw detection and material-property characterization. Although flaw detection is certainly important, the real measurement

G. L. PETERSEN; B. B. CHICK; C. M. FORTUNKO

1992-01-01

385

Car interiors of reinforced composites: a comparison between natural and glass fiber composites  

Technology Transfer Automated Retrieval System (TEKTRAN)

The investigations detected a strong influence of the thermal process characteristics suring compressin molding on the properties of natural fiber reinforced composites. The highest mechanical data was found at processing 220 to 230 degrees C. Higher and lower temperature values resulted in declin...

386

Dual-nanoparticulate-reinforced aluminum matrix composite materials  

NASA Astrophysics Data System (ADS)

Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al4C3) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al4C3. Along with the CNT and the nano-SiC, Al4C3 also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.

Kwon, Hansang; Cho, Seungchan; Leparoux, Marc; Kawasaki, Akira

2012-06-01

387

Fracture properties of composite and glass ionomer dental restorative materials.  

PubMed

The double-torsion technique has been used to determine critical stress intensity factor (K1c) values for a range of composites and glass ionomer cements used in restorative dentistry. From these values and determined elastic modulus (E) and tensile strength (sigma T) values, two other fracture properties: G1c, the critical strain energy release rate and a0, the inherent flaw size, have been evaluated. Glass ionomers have low K1c and high a0 values, coarse particle composites high K1c and high a0 values, microfine materials low K1c and low a0 values and fine particle composites medium to high K1c values and medium to low a0 values. Light curing materials have K1c values according to their group but tend to have lower a0 values than their chemically curing analogues. Glass ionomers have very low G1c values; however, there is no significant difference between the G1c values of the composite groups. The K1c and a0 values have been used to predict relative performance of the materials in highly stressed restorations and wear. PMID:4077896

Goldman, M

1985-09-01

388

Synthesis and Characterization of A Novel Natural Macromolecule Antibacterial Material  

Microsoft Academic Search

A novel natural macromolecule Antibacterial material was synthesized by reaction with carboxymethyl-chitosan, decanoyldimethylammonium and epichlorohydrin. Long chain quaternary ammonium (OGTA) was prepared by reaction with decanoyldimethylammonium and epichlorohydrin, using isopropylalcohol as solvent, at 55degC for 6 hours, and vacuum distillation. The yield was 87 percent. With 0.5 g CMCTS and 2 g OGTA as initiative materials, 0.5 g sodium hydroxide

Jianhua Sun; Nannan Zheng; Rongji Dai; Weiwei Meng; Yulin Deng

2009-01-01

389

Determination of natural actinides and plutonium in marine particulate material  

Microsoft Academic Search

The natural actinides ²²⁷Ac, ²²⁸Th, ²³°Th, ²³²Th, ²³⁴Th, ²³¹Pa, ²³⁸U, and ²³⁴U and the ..cap alpha..-emitting plutonium isotopes are determined in samples of suspended marine particulate material and sediments. Analysis involves total dissolution of the samples to allow equilibration of the natural isotopes with added isotope yield monitors followed by coprecipitation of hydrolyzable metals at pH 7 with natural Fe

Robert F. Anderson; Alan P. Fleer

1982-01-01

390

Infrared Spectroscopic Identification of Chosen Dental Materials and Natural Teeth  

NASA Astrophysics Data System (ADS)

Studies using solid phase infrared spectroscopy in the range of 400 to 4000 wave numbers were conducted in order to quickly identify solid tooth fragments and differentiate them from dental materials used in the dental practice. The frequently employed dental materials were evaluated. Natural chemical structure of permanent teeth obtained from donors of various ages provided the reference material. The infrared vibrations detected in infrared transmission spectra depended on the chemical structure of examined compound. Comparable distinctive peaks in infrared spectra of natural teeth and inorganic dental materials (porcelain) were exhibited. Analogous infrared spectra of dental materials consisting of organic matrix with inorganic fillers were found. In the case of acrylic materials specific organic groups were enhanced. The prepared database of infrared transmission spectra included 23 dental materials, facilitating their appropriate identification. Application of infrared spectroscopy allowed for a quick differential identification of typical dental materials produced from organic compounds for inorganic restorations (porcelain) and of tooth structure-resembling hydroxyapatite and its contaminate forms with fluoride and carbonate ions.

H?dzelek, W.; Marcinkowska, A.; Domka, L.; Wachowiak, R.

2008-08-01

391

Ceramic composite material and process of manufacturing thereof  

US Patent & Trademark Office Database

A MgO/SiC composite material in which SiC particles with nano-meter order in size are dispersed within MgO matrix grains can be prepared by hot-pressing the mixture of fine MgO and SiC powders. Addition of SiC particles in the range of 5 volume percent to 50 volume percent to the MgO matrix increased remarkably the fracture strength and the hardness in a nanometer-order structure of the composite.

Ueda; Hisao (Urawa, JP); Sasaki; Hiroshi (Urawa, JP); Niihara; Koichi (Yokosuka, JP)

1992-07-14

392

The weak interfaces within tough natural composites: experiments on three types of nacre.  

PubMed

Mineralization is a typical strategy used in natural materials to achieve high stiffness and hardness for structural functions such as skeletal support, protection or predation. High mineral content generally leads to brittleness, yet natural materials such as bone, mollusk shells or glass sponge achieve relatively high toughness considering the weakness of their constituents through intricate microstructures. In particular, nanometers thick organic interfaces organized in micro-architectures play a key role in providing toughness by various processes including crack deflection, crack bridging or energy dissipation. While these interfaces are critical in these materials, their composition, structure and mechanics is often poorly understood. In this work we focus on nacre, one of the most impressive hard biological materials in terms of toughness. We performed interfacial fracture tests on chevron notched nacre samples from three different species: red abalone, top shell and pearl oyster. We found that the intrinsic toughness of the interfaces is indeed found to be extremely low, in the order of the toughness of the mineral inclusions themselves. Such low toughness is required for the cracks to follow the interfaces, and to deflect and circumvent the mineral tablets. This result highlights the efficacy of toughening mechanisms in natural materials, turning low-toughness inclusions and interfaces into high-performance composites. We found that top shell nacre displayed the highest interfacial toughness, because of higher surface roughness and a more resilient organic material, and also through extrinsic toughening mechanisms including crack deflection, crack bridging and process zone. In the context of biomimetics, the main implication of this finding is that the interface in nacre-like composite does not need to be tough; the extensibility or ductility of the interfaces may be more important than their strength and toughness to produce toughness at the macroscale. PMID:23084045

Khayer Dastjerdi, Ahmad; Rabiei, Reza; Barthelat, Francois

2012-09-19

393

Composite smart materials using high-volume, microelectronics fabrication techniques  

NASA Astrophysics Data System (ADS)

Smart materials, containing sensors, actuators and processing electronics, are of great potential use in defense and commercial applications from acoustic stealth to medial imaging. While 1:3 composites using PZT rods are now available commercially in limited quantities, composites with individually addressable actuator and sensor arrays are not, nor have conditioning and processing electronics been embedded in the same material. There are several technical and cost reasons for this, including the complexity of interconnections, capacitance of individual elements, thermal dissipation, and the expense of fabricating the material. We have been developing composite materials comprising arrays of miniature actuators fabricated using surface mount capacitor technology, and amenable to automated fabrication using `pick and place' techniques. Miniature actuators with up to 0.1% strain, and operating at 30 V bias and ac swing of +/- 30 V have been fabricated, and placed in 10-by- 10 actuator arrays on Kapton sheets on which circuits have been printed. The arrays were then `potted' in RTV liquid rubbers. Individual actuator motion and multiple actuator influence functions were measured as a function of applied voltage and adjacent actuator motion. These results, along with in-water performance (source level and directivity), are presented.

Winzer, Stephen R.; Shankar, Natarajan; Caldwell, Paul J.; May, Russell G.

1995-05-01

394

Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites  

NASA Astrophysics Data System (ADS)

Natural materials are renowned for their strength and toughness,,,,. Spider dragline silk has a breakage energy per unit weight two orders of magnitude greater than high tensile steel,, and is representative of many other strong natural fibres,,. The abalone shell, a composite of calcium carbonate plates sandwiched between organic material, is 3,000 times more fracture resistant than a single crystal of the pure mineral,. The organic component, comprising just a few per cent of the composite by weight, is thought to hold the key to nacre's fracture toughness,. Ceramics laminated with organic material are more fracture resistant than non-laminated ceramics,, but synthetic materials made of interlocking ceramic tablets bound by a few weight per cent of ordinary adhesives do not have a toughness comparable to nacre. We believe that the key to nacre's fracture resistance resides in the polymer adhesive, and here we reveal the properties of this adhesive by using the atomic force microscope to stretch the organic molecules exposed on the surface of freshly cleaved nacre. The adhesive fibres elongate in a stepwise manner as folded domains or loops are pulled open. The elongation events occur for forces of a few hundred piconewtons, which are smaller than the forces of over a nanonewton required to break the polymer backbone in the threads. We suggest that this `modular' elongation mechanism might prove to be quite general for conveying toughness to natural fibres and adhesives, and we predict that it might be found also in dragline silk.

Smith, Bettye L.; Schäffer, Tilman E.; Viani, Mario; Thompson, James B.; Frederick, Neil A.; Kindt, Johannes; Belcher, Angela; Stucky, Galen D.; Morse, Daniel E.; Hansma, Paul K.

1999-06-01

395

Compositional variation in hydrocarbon reservoirs with natural convection and diffusion  

SciTech Connect

The knowledge of horizontal compositional variation is of prime importance in hydrocarbon reservoir delineation. However, the effect of natural convection on this variation is largely unknown. This work examines the effect of natural convection and diffusion (thermal, pressure and Fickian) on a two-component, single-phase fluid occupying a horizontal cross-sectional reservoir in the presence of a prescribed linear temperature field. The behavior is investigated using a method of successive approximations, which iterates on solution of Poisson`s equation. This behavior is then incorporated in a simplified perturbation solution (in the form of a cubic equation) which not only gives accurate values of horizontal compositional variation, but also clearly shows the interplay of reservoir/fluid properties. The perturbation and the full solutions indicate that a small amount of convection can cause the horizontal composition gradients to increase until a maximum is reached and then decay as 1/k. An alternative scenario is that the gradient asymptotes to a value where the horizontal density derivative approaches zero. Generalization of this perturbative solution to n-components apparently requires the simultaneous solution of n {minus} 1 cubic equations.

Riley, M.F.; Firoozabadi, A. [Reservoir Engineering Research Inst., Palo Alto, CA (United States)

1998-02-01

396

Composite materials - fatigue and fracture; Proceedings of the Symposium, Dallas, TX, October 24, 25, 1984  

SciTech Connect

The aspects of fracture and fatigue in composite materials are discussed in papers which include dynamic delamination crack propagation in graphite/epoxy laminate, the influence of mold coverage upon the notch strength of R25 sheet molding compounds, interface studies of aluminum metal matrix composites, fatigue behavior of continuous-fiber silicon carbide/aluminum composites, and fatigue damage in notched pultruded composite rods. Attention is also given to the fracture of thick graphite/epoxy laminates with part-through surface flaws, failure analysis of a graphite/epoxy laminate subjected to bolt-bearing loads, probabilistic fracture kinetics of natural composites, and fatigue failure mechanisms in unidirectional composites. Also discussed are internal load distribution effects during the fatigue loading of composite laminates, the interrelationship between fiber fracture and ply cracking in graphite/epoxy laminates, a critical-element model of the residual strength and life of fatigue-loaded composite coupons, the response of thick notched laminates subjected to tension-compression cyclic loads, and the effect of ply thickness on longitudinal splitting and delamination in graphite/epoxy under compressive cyclic load.

Hahn, H.T.

1986-01-01

397

DOE/MSU composite material fatigue database: Test methods, materials, and analysis  

SciTech Connect

This report presents a detailed analysis of the results from fatigue studies of wind turbine blade composite materials carried out at Montana State University (MSU) over the last seven years. It is intended to be used in conjunction with the DOE/MSU composite Materials Fatigue Database. The fatigue testing of composite materials requires the adaptation of standard test methods to the particular composite structure of concern. The stranded fabric E-glass reinforcement used by many blade manufacturers has required the development of several test modifications to obtain valid test data for materials with particular reinforcement details, over the required range of tensile and compressive loadings. Additionally, a novel testing approach to high frequency (100 Hz) testing for high cycle fatigue using minicoupons has been developed and validated. The database for standard coupon tests now includes over 4,100 data points for over 110 materials systems. The report analyzes the database for trends and transitions in static and fatigue behavior with various materials parameters. Parameters explored are reinforcement fabric architecture, fiber content, content of fibers oriented in the load direction, matrix material, and loading parameters (tension, compression, and reversed loading). Significant transitions from good fatigue resistance to poor fatigue resistance are evident in the range of materials currently used in many blades. A preliminary evaluation of knockdowns for selected structural details is also presented. The high frequency database provides a significant set of data for various loading conditions in the longitudinal and transverse directions of unidirectional composites out to 10{sup 8} cycles. The results are expressed in stress and strain based Goodman Diagrams suitable for design. A discussion is provided to guide the user of the database in its application to blade design.

Mandell, J.F.; Samborsky, D.D. [Montana State Univ., Bozeman, MT (United States). Dept. of Chemical Engineering

1997-12-01

398

Natural mineral tetrahedrite as a direct source of thermoelectric materials.  

PubMed

We show that a simple powder processing procedure using natural mineral tetrahedrite, the most widespread sulfosalt on earth, provides a low cost, high throughput means of producing thermoelectric materials with high conversion efficiency. These earth-abundant thermoelectrics can open the door to many new and inexpensive power generation opportunities. PMID:23503421

Lu, Xu; Morelli, Donald T

2013-03-18

399

Modeling natural space ionizing radiation effects on external materials  

NASA Astrophysics Data System (ADS)

Predicting the effective life of materials for space applications has become increasingly critical with the drive to reduce mission cost. Programs have considered many solutions to reduce launch costs including novel, low mass materials and thin thermal blankets to reduce spacecraft mass. Determining the long-term survivability of these materials before launch is critical for mission success. This presentation will describe an analysis performed on the outer layer of the passive thermal control blanket of the Hubble Space Telescope. This layer had degraded for unknown reasons during the mission, however ionizing radiation (IR) induced embrittlement was suspected. A methodology was developed which allowed direct comparison between the energy deposition of the natural environment and that of the laboratory generated environment. Commercial codes were used to predict the natural space IR environment, model energy deposition in the material from both natural and laboratory IR sources, and design the most efficient test. Results were optimized for total and local energy deposition with an iterative spreadsheet. This method has been used successfully for several laboratory tests at the Marshall Space Flight Center. The study showed that the natural space IR environment, by itself, did not cause the premature degradation observed in the thermal blanket.

Altstatt, Richard L.; Edwards, David L.

2000-10-01

400

Using Natural Materials for Educational Toys: Examples from Ghana.  

ERIC Educational Resources Information Center

|Describes educational toys that are made from natural and readily available materials in Ghana. Directions and diagrams for the pawpaw-leaf horn, milk-tin helicopter, pen-top propeller, bow and arrow, spinning top, and feather helicopter are included. (DDR)|

William, Musah; Preston, Christine

1998-01-01

401

Natural tissue microenvironmental conditions modulate adhesive material performance.  

PubMed

We designed and optimized tissue-responsive adhesive materials by matching material and tissue properties. A two-component material based on dextran aldehyde and dendrimer amine provides a cohesive gel through aldehyde-amine cross-linking and an adhesive interface created by a dextran aldehyde-selective reaction with tissue amines. By altering aldehyde-amine chemistry, we examined how variations in tissue surfaces (serosal amine density in the duodenum, jejunum, and ileum) affect interactions with adhesive materials of varied compositions (aldehyde content). Interestingly, the same adhesive formulation reacts differentially with the three regions of the small intestine as a result of variation in the tissue amine density along the intestinal tract, affecting the tissue-material interfacial morphology, adhesion strength, and adhesive mechanical properties. Whereas tissues provide chemical anchors for interaction with materials, we were able to tune the adhesion strength for each section of the small intestine tissue by altering the adhesive formulation using a two-component material with flexible variables aimed at controlling the aldehyde/amine ratio. This tissue-specific approach should be applied to the broad spectrum of biomaterials, taking into account specific microenvironmental conditions in material design. PMID:23046479

Oliva, Nuria; Shitreet, Sagi; Abraham, Eytan; Stanley, Butch; Edelman, Elazer R; Artzi, Natalie

2012-10-18

402

Compendium of Material Composition Data for Radiation Transport Modeling  

SciTech Connect

Introduction Meaningful simulations of radiation transport applications require realistic definitions of material composition and densities. When seeking that information for applications in fields such as homeland security, radiation shielding and protection, and criticality safety, researchers usually encounter a variety of materials for which elemental compositions are not readily available or densities are not defined. Publication of the Compendium of Material Composition Data for Radiation Transport Modeling, Revision 0, in 2006 was the first step toward mitigating this problem. Revision 0 of this document listed 121 materials, selected mostly from the combined personal libraries of staff at the Pacific Northwest National Laboratory (PNNL), and thus had a scope that was recognized at the time to be limited. Nevertheless, its creation did provide a well-referenced source of some unique or hard-to-define material data in a format that could be used directly in radiation transport calculations being performed at PNNL. Moreover, having a single common set of material definitions also helped to standardize at least one aspect of the various modeling efforts across the laboratory by providing separate researchers the ability to compare different model results using a common basis of materials. The authors of the 2006 compendium understood that, depending on its use and feedback, the compendium would need to be revised to correct errors or inconsistencies in the data for the original 121 materials, as well as to increase (per users suggestions) the number of materials listed. This 2010 revision of the compendium has accomplished both of those objectives. The most obvious change is the increased number of materials from 121 to 372. The not-so-obvious change is the mechanism used to produce the data listed here. The data listed in the 2006 document were compiled, evaluated, entered, and error-checked by a group of individuals essentially by hand, providing no library file or mechanism for revising the data in a consistent and traceable manner. The authors of this revision have addressed that problem by first compiling all of the information (i.e., numbers and references) for all the materials into a single database, maintained at PNNL, that was then used as the basis for this document.

McConn, Ronald J.; Gesh, Christopher J.; Pagh, Richard T.; Rucker, Robert A.; Williams III, Robert

2011-03-04

403

Naturally and synthetic smart composite biomaterials for tissue regeneration.  

PubMed

The development of smart biomaterials for tissue regeneration has become the focus of intense research interest. More opportunities are available by the composite approach of combining the biomaterials in the form of biopolymers and/or bioceramics either synthetic or natural. Strategies to provide smart capabilities to the composite biomaterials primarily seek to achieve matrices that are instructive/inductive to cells, or that stimulate/trigger target cell responses that are crucial in the tissue regeneration processes. Here, we review in-depth, recent developments concerning smart composite biomaterials available for delivery systems of biofactors and cells and scaffolding matrices in tissue engineering. Smart composite designs are possible by modulating the bulk and surface properties that mimic the native tissues, either in chemical (extracellular matrix molecules) or in physical properties (e.g. stiffness), or by introducing external therapeutic molecules (drugs, proteins and genes) within the structure in a way that allows sustainable and controllable delivery, even time-dependent and sequential delivery of multiple biofactors. Responsiveness to internal or external stimuli, including pH, temperature, ionic strength, and magnetism, is another promising means to improve the multifunctionality in smart scaffolds with on-demand delivery potential. These approaches will provide the next-generation platforms for designing three-dimensional matrices and delivery systems for tissue regenerative applications. PMID:22465488

Pérez, Román A; Won, Jong-Eun; Knowles, Jonathan C; Kim, Hae-Won

2012-03-20

404

Power loss separation in Fe-based composite materials  

NASA Astrophysics Data System (ADS)

The frequency dependence of total losses measured in the frequency range from dc to 1 kHz of two Fe-based soft magnetic composites (prepared by compaction of an ASC 100.29 iron powder mixture with 10 vol% of commercial thermoset resin and of a Somaloy® 700 powder) was analyzed. We found out that hysteresis losses (per volume unit) are higher for the composite with lower volume concentration of iron particles (i.e. mixture of iron with resin) and consequently weaker magnetic interaction between particles. On the other hand, higher specific resistivity of the sample with lower magnetic fraction causes lower contribution of eddy current losses to the total losses. A linear dependence of the total energy losses on frequency was observed and from them the contribution of excess losses was obtained. The detailed study of the excess losses resulted in an explanation of the frequency dependence of these losses in composite materials.

Kollár, Peter; Bir?áková, Zuzana; Füzer, Ján; Bureš, Radovan; Fáberová, Mária

2013-02-01

405

The percolation staircase model and its manifestation in composite materials  

NASA Astrophysics Data System (ADS)

We studied the tunneling percolation conductivity dependence on the site or bond occupation probability in the square lattice. The model predicts that in both, lattice and continuum systems in which there is a hierarchy of the local conductances, the dependence of the global conductivity on the site or volume occupation probability will yield a conductivity staircase. In particular we evaluate the implications of the staircase on the critical behavior of the conductivity. We then show experimental evidence for the predicted percolation-tunneling staircase in a Ag-Al2O3 granular metal system and in a carbon black-polymer composite. Following that, we propose that for carbon nanotube (CNT) polymer composites the data in the literature give ample support to a percolation-dispersion staircase behavior. The implication of the present findings on the percolation-hopping problem in composite materials is also discussed.

Balberg, I.; Azulay, D.; Goldstein, Y.; Jedrzejewski, J.; Ravid, G.; Savir, E.

2013-10-01

406

Degradation of experimental composite materials and in vitro wear simulation  

NASA Astrophysics Data System (ADS)

The material, mechanical, and clinical aspects of surface degradation of resin composite dental restorative materials by in vitro wear simulation continues to be an area of active research. To investigate wear mechanisms, a series of experimental resin composites with variable and controlled filler particle shape and loading were studied by in vitro wear simulation. The current investigation utilized a simulation that isolated the wear environment, entrapped high and low modulus debris, and evaluated the process including machine and fluid flow dynamics. The degradation was significantly affected by filler particle shape and less by particle loading. The spherical particle composites demonstrated wear loss profiles suggesting an optimized filler loading may exist. This was also demonstrated by the trends in the mechanical properties. Very little difference in magnitude was noted for the wear of irregular particle composites as a function of particulate size; and as a group they were more wear resistant than spherical particle composites. This was the result of different mechanisms of wear that were correlated with the three-dimensional particle shape. The abrasive effects of the aggregate particles and the polymeric stabilization of the irregular shape versus the destabilization and "plucking" of the spherical particles resulted in an unprotected matrix that accounted for significantly greater wear of spherical composite. A model and analysis was developed to explain the events associated with the progressive material wear loss. The initial phase was explained by fatigue-assisted microcracking and loss of material segments in a zone of high stress immediately beneath a point of high stress contact. The early phase was characterized by the development of a small facet primarily by fatigue-assisted microcracking. Although the translation effects were minimal, some three-body and initial two-body wear events were also present. In the late phases, the abrasive effects of the debris aggregate predominated the wear process. The non-linear rate of wear loss was accelerated as the facet deepened. Physical effects, such as thermal fatigue, and chemical effects were less important but contributed to the degradation process. This study provides new insight into the role(s) of high modulus third body debris in the wear of dental composites.

Givan, Daniel Allen

2001-12-01

407

Carbonization of wood at 400°C for composite materials  

NASA Astrophysics Data System (ADS)

The carbonization process for large pieces of wood was investigated to produce a solid carbonized wood skeleton precursor that retains the cellular structure of the wood without the formation of cracks and with reduced longitudinal deformation. Two carbonization schedules were designed for the conversion of sugar maple (Acer saccharum) and southern pine ( Pinus spp) into amorphous carbon at a heat treatment temperature of 400°C. Samples from commercial lumber were carbonized to produce the materials. Each schedule was designed meticulously through DTA-TGA for each wood species. The materials were characterized by their average yields, dimensional changes, density, porosity, SEM and mechanical testing. Also, the materials were used as solid carbon skeletons for making resin-infused carbon composites. Structural epoxy resin was infused into the carbon material template and cured at a maximum temperature of 125°C. The depth of the resin infusion was assessed by SEM examination and the retention was analyzed by total weight gain. The strength and the stiffness of the composite materials were evaluated through mechanical testing. It was demonstrated that southern pine and sugar maple should require different heat treatment schedules for carbonization. The schedules were able to reduce the longitudinal deformation and to keep the final products free of cracks. The yield averaged around 28% for both southern pine and sugar maple. Carbonized southern pine exhibited lower density and higher porosity than carbonized sugar maple. The resin treatment increased specific gravity of carbonized materials by 9.6% and 11.6% for maple and southern pine respectively. The resin infusion improved the average MOR values by 140% and 275%. MOE of the composites was similar to that of pure epoxy.

Randrianarisoa, Bernard Laurent

408

Material properties and fractography of an indirect dental resin composite  

PubMed Central

Objectives Determination of material and fractographic properties of a dental indirect resin composite material. Methods A resin composite (Paradigm, 3M-ESPE, MN) was characterized by strength, static elastic modulus, Knoop hardness, fracture toughness and edge toughness. Fractographic analyses of the broken bar surfaces was accomplished with a combination of optical and SEM techniques, and included determination of the type and size of the failure origins, and fracture mirror and branching constants. Results The flexure test mean strength ± standard deviation was 145 MPA ± 17 MPa, and edge toughness, Te, was 172 N/mm ±12 N/mm. Knoop hardness was load dependent, with a plateau at 0.99 GPa ± .02 GPa. Mirrors in the bar specimens were measured with difficulty, resulting in a mirror constant of approximately 2.6 MPa·m1/2. Fracture in the bar specimens initiated at equiaxed material flaws that had different filler concentrations that sometimes were accompanied by partial microcracks. Using the measured flaw sizes, which ranged from 35 µm to 100 µm in size, and estimates of the stress intensity shape factors, fracture toughness was estimated to be 1.1 MPa·m1/2 ± 0.2 MPa·m1/2. Significance Coupling the flexure tests with fractographic examination enabled identification of the intrinsic strength limiting flaws. The same techniques could be useful in determining if clinical restorations of similar materials fail from the same causes. The existence of a strong load-dependence of the Knoop hardness of the resin composite is not generally mentioned in the literature, and is important for material comparisons and wear evaluation studies. Finally, the edge toughness test was found promising as a quantitative measure of resistance to edge chipping, an important failure mode in this class of materials.

Quinn, Janet B.; Quinn, George D.

2011-01-01

409

Composite materials for Ericsson-like magnetic refrigeration cycle  

SciTech Connect

The ideal magnetic Ericsson refrigeration cycle should have a constant induced magnetic entropy change as a function of temperature over the whole refrigeration range. To realize this condition using composite materials, a numerical method has been developed to determine the optimum proportions of the component materials in such refrigerants. This paper investigates the effects of increasing the number (n) of the components on the constancy of the magnetic entropy change of the composite ({Delta}S{sub com}), and suggests some new composite refrigerants. For this purpose, the Gd{sub 1{minus}x}{endash}Dy{sub x} (with x=0, 0.12, 0.28, 0.49, and 0.70) alloys, have been used. The values of {Delta}S have been calculated both from mean-field theory as well as from experimental magnetization curves of these alloys, in the 0.1{endash}7 T magnetic field range and the 200{endash}300 K temperature range. Two sets of composite materials have then been proposed as refrigerants, operating, respectively, over the temperature range 240{endash}290 K and 210{endash}290 K. The {Delta}S data of the individual Gd{endash}Dy alloys were then used to calculate the optimum mass ratio of the composites. The resultant {Delta}S{sub com} is practically constant in the required temperature range and amounts to 8.0 and 7.3 J/kgK for the two respective sets. The results show that a subsequent increase of n can improve the constancy of the value of {Delta}S{sub com}, and, hence, the corresponding refrigerant should operate more efficiently. Thus, it is found that the appropriate values of n are 3 and 4, respectively, for the first and the second set. {copyright} {ital 1997 American Institute of Physics.}

Smaieli, A.; Chahine, R. [Institut de Recherche sur l`Hydrogene, Universite du Quebec a Trois-Rivieres, C.P. 500, Trois-Rivieres, Quebec, Canada, G9A 5H7 (CANADA)

1997-01-01

410

The dynamic inelastic behavior in fiber reinforced composite materials  

SciTech Connect

Accurately simulating the complete dynamic behavior, elastic and inelastic, of engineering structures composed of fiber reinforced composite materials can be accomplished by integrating three components: (1) a physically based micromechanical material model that accounts for the experimentally observed mechanisms producing the inelastic behavior; (2) a dynamic three-dimensional continuum simulation capability in which the physically based micromechanical material model is incorporated; and (3) a complete set of robust dynamic experiments. These experiments are used (1) to establish the microstructural mechanisms that produce inelastic behavior and (2) to validate the dynamic simulation capability. This paper focuses on the implementation of a physically based micromechanical material model into an explicit 3D finite element code and shows the experimental comparison.

Haberman, K.S.; Bennett, J.G.; Liu, Cheng [and others

1997-03-01

411

Functionally Graded Dual-Nanoparticulate-Reinforced Aluminum Matrix Composite Materials  

NASA Astrophysics Data System (ADS)

Functionally graded carbon nanotubes (CNT) and nano Silicon carbide (nSiC) reinforced aluminum (Al) matrix composite materials were fully densified by a simple ball milling and hot-pressing processes. The nSiC was used as a physical mixing agent to increase dispersity of the CNT in the Al particles. It was observed that the CNT was better dispersed in the Al particles with a nSiC mixing agent compared to without it used. SEM micrograph showed that the interface of the each layers had very tightly adhesion without any serious pores and micro-cracks. This functionally graded dual-nanoparticulate-reinforced Al matrix composite by powder metallurgical approach could also be applied to comples matrix materials.

Kwon, Hansang; Lee, Gil-Geun; Leparoux, Marc; Kawasaki, Akira

2013-03-01

412

Degradation, fatigue and failure of resin dental composite materials  

PubMed Central

The intent of this article is to review the numerous factors that affect the mechanical properties of particle or fiber filler containing, indirect dental resin composite materials. The focus will be on degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed mode loading on the flexure strength and fracture toughness. Next several selected papers will be examined in detail with respect to mixed and cyclic loading and then an examination of 3D tomography using multiaxial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection) and after that time period from secondary decay.

Drummond, James L.

2008-01-01

413

Degradation, Fatigue, and Failure of Resin Dental Composite Materials  

SciTech Connect

The intent of this article is to review the numerous factors that affect the mechanical properties of particle- or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

Drummond, J.L. (UIC)

2008-11-03

414

Natural radioactivity in common building construction and radiation shielding materials  

NASA Astrophysics Data System (ADS)

Commonly used building construction materials, radiation shielding bricks, hematite aggregate and other materials have been analyzed for the activity concentration of the natural radionuclides, namely 238U, 232Th and 40K, besides the radon exhalation rates. The activity concentration for 238U, 232Th and 40K varies from 29±1 to 98±4 Bq kg -1, 20±2 to 112±2.8 Bq kg -1, and 200±8 to 1908±15.6 Bq kg -1, respectively, in various materials studied in the present work. Radon activity in the various samples varies from 190±11 to 313±14 Bq m -3, the mass exhalation rate for radon varies from 1.05±0.07 to 1.92±0.09 mBq kg -1 h -1 and surface exhalation rate varies from 9.0±0.30 to 19.8±22 mBq m -2 h -1 for materials under investigation. The activity concentrations of uranium, thorium and potassium and radon exhalation rates vary from material to material. Thorium and potassium activity in the granite materials is higher, followed by radiation shielding material compared to other common construction materials. Uranium activity concentration is higher in cement as compared to radiation shielding material and other common construction materials. The absorbed dose varies from 23 to 185 nGy h -1 and the indoor annual effective dose varies from 0.11 to 0.91 mSv. The outdoor annual effective dose varies from 0.03 to 0.23 mSv. The absorbed dose and the effective dose equivalent are found to be higher in the granite, followed by radiation shielding material and other common construction materials. In all the samples, the activity concentration of 238U, 232Th and 40K is found below the permissible levels. A strong correlation coefficient has been observed between radon activity and surface exhalation rate (correlation coefficient=0.899).

Sonkawade, R. G.; Kant, K.; Muralithar, S.; Kumar, R.; Ramola, R. C.

415

Intermetallic and titanium matrix composite materials for hypersonic applications  

SciTech Connect

As part of the French Program of Research and Technology for Advanced Hypersonic Propulsion (PREPHA) which was launched in 1992 between Aerospatiale, Dassault Aviation, ONERA, SNECMA and SEP, an important work is specially devoted to the development of titanium and intermetallic composite materials for large airframe structures. At Dassault Aviation, starting from a long experience in Superplastic Forming - Diffusion Bonding (SPF-DB) of titanium parts, the effort is brought on the manufacturing and characterization of composites made from Timet beta 21S or IMI 834 foils and Textron SCS6 fiber fabrics. At `Aersopatiale Espace & Defence`, associated since a long time about intermetallic composite materials with university research laboratories, the principal effort is brought on plasma technology to develop the gamma titanium aluminide TiAl matrix composite reinforced by protected silicon carbide fibers (BP SM 1240 or TEXTRON SCS6). The objective, is to achieve, after 3 years of time, to elaborate a medium size integrally stiffened panel (300 x 600 sq mm).

Berton, B.; Surdon, G.; Colin, C. [Dassault Aviation, Saint-Cloud (France)]|[Aersopatiale Space & Defence, St Medard en Jalles (France)

1995-09-01

416

Conducting polymer composite materials for smart microwave windows  

NASA Astrophysics Data System (ADS)

Samples of poly(aniline)-silver-polymer electrolyte particulate composites have been characterized at microwave frequencies when small d.c. electric fields are applied across them in both coaxial line and waveguide measurement test sets. The experimental data shows that the initial conductivity of the materials is dependent on the concentration of sliver metal and suggest that changes in resistance due to chemical switching take place, at least in part, in the manufacture of the composites. When silver is used as the electrodes, the experimental data show that changes in the slope of the cyclic voltammograms coincide with large changes in microwave reflectivity or transmission consistent with increasing conductivity of the composites when fields are applied. The reverse change occurs when the fields are removed. Measurements have shown that the composites are able to switch between the two impedance stats in times of less than one second for well over a million cycles with no apparent depreciation in material properties. Large area films have also been prepared and studied using the 'free space' technique.

Barnes, Alan; Lees, K.; Wright, Peter V.; Chambers, Barry

1999-07-01

417

Polyvinyl alcohol-cellulose composite: a taste sensing material  

Microsoft Academic Search

There are reports of fabrication of taste sensor by adsorbing lipids into Millipore filter paper. With this lipid based sensor,\\u000a it has been found that the taste sensing efficiency of membrane can be remarkably improved. We have made an attempt to prepare\\u000a taste sensor material by using functionalized polymer without any lipid. PVA-cellulose composite has been modified to use\\u000a as

Sarmishtha Majumdar; Basudam Adhikari

2005-01-01

418

Mixed-mode fracture in fiber-reinforced composite materials  

Microsoft Academic Search

Problems of mixed-mode crack extension in unidirectionally fiber-reinforced composite materials are examined. Previous studies have been aimed at establishing an appropriate criterion for mixed-mode matrix fracture by using specimens in the form of multi-layer laminates. One common difficulty encountered has been the strong dependence of fracture on specimen geometry due to insufficient analytical rigor in formulating and solving the test

Binienda

1987-01-01

419

Effective properties of suspensions, composites and porous materials  

Microsoft Academic Search

Three effective properties of heterogeneous systems are discussed from the viewpoint of rational mechanics and micromechanics: viscosity of suspensions and the tensile modulus and thermal conductivity of solid composites, including porous materials. Rigorous bounds (Voigt–Reuss and Hashin–Shtrikman bounds) are given as well as model relations for prediction and fitting purposes (dilute approximations, power-law relations, exponential relations, Coble–Kingery relations and new

Willi Pabst; Eva Gregorová; Gabriela Tichá

2007-01-01

420

Synthesis of Si 3N 4celsian composite materials  

Microsoft Academic Search

The synthesis of Si3N4-celsian composite materials was studied in this paper. To obtain celsian, two different types of additives were used. In the first case the appropriate mixture of BaCO3, Al2O3 and SiO2 was added to Si3N4, while in the second case a Ba-A-zeolite, previously heated at 850°C, was used as an additive. Mixtures of Si3N4 and the sintering aids

S Boškovi?; D Kosanovi?; V Dondur; R Dimitrijevi?

2000-01-01

421

Composites of Calcium Phosphate and Polymers as Bone Substitution Materials  

Microsoft Academic Search

The state of the art of calcium phosphate\\/polymer composites for bone substitution is reviewed. Many combinations are possible\\u000a which were proposed to improve the mechanical properties and the biocompatibility. However, the way from the laboratory to\\u000a the clinical application is long, and potential candidates for new bone substitution materials have to meet many different\\u000a requirements.

Markus Neumann; Matthias Epple

2006-01-01

422

Novel Composite Materials for SOFC Cathode-Interconnect Contact  

Microsoft Academic Search

This report summarized the research efforts and major conclusions of our University Coal Research Project, which focused on developing a new class of electrically-conductive, Cr-blocking, damage-tolerant Ag-perovksite composite materials for the cathode-interconnect contact of intermediate-temperature solid oxide fuel cell (SOFC) stacks. The Ag evaporation rate increased linearly with air flow rate initially and became constant for the air flow rate

J. H. Zhu; L. T. Wilkinson; J. M. Shoulders

2009-01-01

423

Calcium phosphate-based ceramic and composite materials for medicine  

NASA Astrophysics Data System (ADS)

The topical problems in chemistry and technology of materials based on calcium phosphates aimed at both the replacement of damaged bone tissue and its regeneration are discussed. Specific features of the synthesis of nanocrystalline powders and the fabrication of ceramic implants are described. Advances in the development of porous scaffolds from resorbable and osteoconductive calcium phosphates and of hybrid composites that form the basis of bone tissue engineering are considered.

Barinov, Sergei M.

2010-01-01

424

Additional effective medium parameters for composite materials (excess surface currents).  

PubMed

Modified boundary conditions for composite material are suggested. The modified RT-retrieval procedure yields bulk values of effective impedance and refractive index, which are independent of system size and boundary realization, whereas the conductivities of the excess surface currents depend on the property of the interface. Simultaneous treatment of all the possible realizations of the system removes the dependence. The accuracy of the latter procedure is the same as the usage of static effective parameters, namely k(eff)d. PMID:21451696

Vinogradov, A P; Ignatov, A I; Merzlikin, A M; Tretyakov, S A; Simovski, C R

2011-03-28

425

Fabrication of a nanostructured gold-polymer composite material  

Microsoft Academic Search

.  A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent\\u000a for both the AP and the water solution of HAuCl4. It was found that

K. Mallick; M. Witcomb; M. Scurrell

2006-01-01

426

AlSiC composite materials in IGBT power modules  

Microsoft Academic Search

The reliability of IGBT modules is limited by thermal fatigue of soft solder layers due to different coefficients of thermal expansion. A thermally matching conducting material can be produced from Al matrix composites containing high volume fractions of SiC particulates. Variously processed prototypes of AlSiC baseplates were investigated with a view to their suitability for IGBT power modules. The volume

G. Mitic; H. P. Degischer; G. Lefranc; T. Licht

2000-01-01

427

Reclaiming a natural beauty: whole-organ engineering with natural extracellular materials  

PubMed Central

The ability to engineer whole organs as replacements for allografts and xenografts is an ongoing pursuit in regenerative medicine. While challenges remain, including systemic tissue integration with angiogenesis, lymphatiogenesis and neurogenesis, ongoing efforts are working to develop novel technologies to produce implantable engineered scaffolds and potentially engineered whole organs. Natural extracellular matrix materials, commonly utilized in vitro, are now being used as effective, natural, acellular allografts, and are being integrated into nanoscale scaffolds and matrices with programmable responsiveness. Based on the significant use of natural scaffolds for tissue regeneration and bioengineering strategies, this review focuses on recent and ongoing efforts to engineer whole organs, such as the tooth, featuring natural extracellular matrix molecules.

Traphagen, Samantha; Yelick, Pamela C

2009-01-01

428

27 CFR 555.221 - Requirements for display fireworks, pyrotechnic compositions, and explosive materials used in...  

Code of Federal Regulations, 2013 CFR

...false Requirements for display fireworks, pyrotechnic compositions, and explosive materials used in assembling fireworks or articles pyrotechnic. 555...221 Requirements for display fireworks, pyrotechnic compositions,...

2013-04-01

429

27 CFR 555.221 - Requirements for display fireworks, pyrotechnic compositions, and explosive materials used in...  

Code of Federal Regulations, 2011 CFR

... true Requirements for display fireworks, pyrotechnic compositions, and explosive materials used in assembling fireworks or articles pyrotechnic. 555...221 Requirements for display fireworks, pyrotechnic compositions,...

2011-04-01

430

Ultrasonic nondestructive testing of composite materials using disturbed coincidence conditions  

NASA Astrophysics Data System (ADS)

In this contribution we present a new method detecting changes in the composite material's acoustic behavior by analyzing disturbed coincidence conditions on plate-like test samples. The coincidence condition for an undamaged GFRP test sample has been experimentally identified using Schlieren measurements. Disturbances of this condition follow from a disturbed acoustic behavior of the test sample which is an indicator for local damages in the region inspected. An experimental probe has been realized consisting of two piezoceramic elements adhered to the nonparallel sides of an isosceles trapezoidal body made of silicone. The base angles of the trapezoidal body have been chosen such that the incident wave meets pre-measured condition of coincidence. The receiving element receives the geometric reflection of the acoustic wave scattered at the test sample's surface which corresponds to the non-coupled part of the incident wave as send by the sending element. Analyzing the transfer function or impulse response of the electro-acoustic system (transmitter, scattering at test sample, receiver), it is possible to detect local disturbances with respect to Cramer's coincidence rule. Thus, it is possible to realize a very simple probe for local ultrasonic nondestructive testing of composite materials (as well as non-composite material) which can be integrated in a small practical device and is good for small size inspection areas.

Bause, F.; Olfert, S.; Schröder, A.; Rautenberg, J.; Henning, B.; Moritzer, E.

2012-05-01

431

Measurement of Poisson's ratio of dental composite restorative materials.  

PubMed

The aim of this study was to determine the Poisson ratio of resin-based dental composites using a static tensile test method. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid-modified (F2000), and flowable (Filtek Flowable [FF]) composites. The Poisson ratio of the materials were determined after 1 week conditioning in water at 37 degrees C. The tensile test was performed with using a uniaxial testing system at crosshead speed of 0.5 mm/min. Data was analysed using one-way ANOVA/post-hoc Scheffe's test and Pearson's correlation test at significance level of 0.05. Mean Poisson's ratio (n=8) ranged from 0.302 to 0.393. The Poisson ratio of FF was significantly higher than all other composites evaluated, and the Poisson ratio of A110 was higher than Z100, Z250 and F2000. The Poisson ratio is higher for materials with lower filler volume fraction. PMID:14751729

Chung, Sew Meng; Yap, Adrian U Jin; Koh, Wee Kiat; Tsai, Kuo Tsing; Lim, Chwee Teck

2004-06-01

432

Natural-fiber-reinforced polymer composites in automotive applications  

NASA Astrophysics Data System (ADS)

In the past decade, natural-fiber composites with thermoplastic and thermoset matrices have been embraced by European car manufacturers and suppliers for door panels, seat backs, headliners, package trays, dashboards, and interior parts. Natural fibers such as kenaf, hemp, flax, jute, and sisal offer such benefits as reductions in weight, cost, and CO2, less reliance on foreign oil sources, and recyclability. However, several major technical considerations must be addressed before the engineering, scientific, and commercial communities gain the confidence to enable wide-scale acceptance, particularly in exterior parts where a Class A surface finish is required. Challenges include the homogenization of the fiber's properties and a full understanding of the degree of polymerization and crystallization, adhesion between the fiber and matrix, moisture repellence, and flame-retardant properties, to name but a few.

Holbery, James; Houston, Dan

2006-11-01

433

Mechanics of composite materials with curved structures and elements of constructions (review)  

Microsoft Academic Search

One of the major problems in composite material mechanics are problems of mechanics of these materials and elements of constructions fabricated from these materials associated with special features of structure of the composites. Among these specific characteristics of composite materials structure, file bending of reinforcing elements is of considerable importance. As is well known, these bent, curved structural elements may

S. D. Akbarov; A. N. Guz’; N. Yahnioglu

1998-01-01

434

Semi-annual report on materials research in support of superconducting machinery. Final report. [Composite materials  

Microsoft Academic Search

The following five areas are discussed: advanced composites, elastic properties, fatigue resistance and fracture toughness, magnetothermal conductivity, and thermal conductivity. Material properties were studied over the temperature range 4 to 300°K. Materials studied include: aluminum alloy 5083, copper--0.3 cadmium--0.3 tin, copper--28 nickel, iron--48 nickel, 3.5 Ni and 9 Ni steels, titanium--4 aluminum--6 vanadium, titanium--5 aluminum--2.5 tin, stainless steel 21-6-9, several

R. P. Reed; J. G. Hust; M. B. Kasen; H. M. Ledbetter; H. I. McHenry

1976-01-01

435

Synthesis & Properties of Nano-Composite Thermoelectric Materials  

NASA Astrophysics Data System (ADS)

PbTe nanocrystals have been grown in our labs by chemical vapor deposition. These materials grow in size selective regions exhibiting very high yield and have size distributions of around 100 nm to 1000 nm. These nano-materials are incorporated into a bulk matrix, making a composite material in hopes of achieving a higher thermoelectric performance due to the increased phonon scattering that the nano-materials are expected to exhibit, as well as potential for enhancement of their Seebeck coefficient. Some of the advantages as well as the challenges will be discussed. These nanocomposites give a new level of potential control as a tuning parameter with which to vary the materials' thermoelectric properties. In addition, Bi2Te3, another state of the art thermoelectric material and skutterudites (CoSb3) have been synthesized as nanomaterials using hydrothermal techniques. A brief discussion of the synthesis techniques, the characterization techniques and highlights of several systems of materials will be presented. In collaboration with Xiaohua Ji, Jian He, Bo Zhang, Nick Gothard, and Paola Alboni, Dept. of Physics, Clemson University.

Tritt, Terry

2007-03-01

436

Naturally Occurring Radioactive Materials in Cargo at US Borders  

SciTech Connect

In the U.S. and other countries, large numbers of vehicles pass through border crossings each day. The illicit movement of radioactive sources is a concern that has resulted in the installation of radiation detection and identification instruments at border crossing points. This activity is judged to be necessary because of the possibility of an act of terrorism involving a radioactive source that may include any number of dangerous radionuclides. The problem of detecting, identifying, and interdicting illicit radioactive sources is complicated by the fact that many materials present in cargo are somewhat radioactive. Some cargo contains naturally occurring radioactive material or technologically-enhanced naturally occurring radioactive material that may trigger radiation portal monitor alarms. Man-made radioactive sources, especially medical isotopes, are also frequently observed and produce alarms. Such nuisance alarms can be an operational limiting factor for screening of cargo at border crossings. Information about the nature of the radioactive materials in cargo that can interfere with the detection of radionuclides of concern is necessary. This paper provides such information for North American cargo, but the information may also be of use to border control officials in other countries. (PIET-43741-TM-361)

Kouzes, Richard T.; Ely, James H.; Evans, John C.; Hensley, Walter K.; Lepel, Elwood A.; McDonald, Joseph C.; Schweppe, John E.; Siciliano, Edward R.; Strom, Daniel J.; Woodring, Mitchell L.

2006-01-01

437

Overview of naturally occurring Earth materials and human health concerns  

NASA Astrophysics Data System (ADS)

The biosphere and the Earth's critical zone have maintained a dynamic equilibrium for more than 3.5 billion years. Except for solar energy, almost all terrestrial substances necessary for life have been derived from near-surface portions of the land, hydrosphere, and atmosphere. If aggregate biological activities are less than the rate of nutrient supply and/or resource renewal, sustained population growth is possible. Where the replenishment rate of a life-sustaining Earth material is finite, usage may reach a condition of dynamic equilibrium in which biological consumption equals but on average cannot exceed the overall supply. Although large, most natural resources are present in finite abundances; for such commodities, excessive present-day human utilization reduces future availability, and thus the ultimate planetary carrying capacity for civilization. Intensive use of Earth materials has enhanced the quality of life, especially in the developed nations. Still, natural background levels, and Earth processes such as volcanic eruptions, as well as human activities involving agriculture, construction, and the extraction, refining, and transformation of mineral resources have led to harmful side effects involving environmental degradation and public health hazards. Among naturally and anthropogenically induced risks are bioaccessible airborne dusts and gases, soluble pollutants in agricultural, industrial, and residential waters, and toxic chemical species in foods and manufactured products. At appropriate levels of ingestion, many Earth materials are necessary for existence, but underdoses and overdoses have mild to serious consequences for human health and longevity.This overview briefly sketches several natural resource health hazards. Included are volcanic ash + aerosols + gases, mineral dusts, non-volcanic aerosols + nanoparticles, asbestos + fibrous zeolites, arsenic, fluorine, iodine, uranium + thorium + radium + radon + polonium, selenium, mercury, copper, lead, chromium, and cadmium. Also noted are health effects of natural disasters, and an obligatory future sustainable consumption of natural resources. Not treated are the overwhelming adverse effects of malnutrition, lack of potable water, inadequate sanitation, fossil fuel usage, mining, manufacturing, and agricultural pollution, or environmental pathogens, nor are the important impacts of complex mixtures of Earth materials considered.With rise of the worldwide information network, economic globalization, and the industrial thrust of Developing Nations, the achievement of natural resource sustainability has emerged as a strategic imperative. Accompanying increased rates of Earth materials consumption and attendant environmental change, substantially improved, universal public health will require a major global effort, integrating collaborations among geoscientists, medical researchers, and epidemiologists. Governments and NGOs must provide important support of such cooperative efforts, and both health and Earth scientists must cross disciplinary and national boundaries.

Ernst, W. G.

2012-10-01

438

Natural radioactivity in building materials used in Changzhi, China.  

PubMed

The natural radioactivity levels of the commonly used building materials collected from Changzhi, China was analysed using gamma-ray spectroscopy. The activity concentrations of (226)Ra, (232)Th and (40)K in the investigated building materials range from 14.6 to 131.2, from 9.9 to 138.8 and from 96.1 to 819.0 Bq kg(-1), respectively. The results were compared with the reported data of other countries and with the worldwide mean activity of soil. The external and internal hazard indices and gamma index were calculated to assess the radiation hazard to residents. The external hazard index of all building materials are less than unity, while the internal hazard and gamma indexes of hollow brick and gravel aggregate exceed unity. The study shows that the investigated hollow brick and gravel aggregate are not suitable for use as building materials in dwellings. PMID:23407886

Yang, Guang; Lu, Xinwei; Zhao, Caifeng; Li, Nan

2013-02-13

439

Adsorption of volatile hydrocarbons on natural zeolite-clay material  

Microsoft Academic Search

This study investigated the vapor-phase sorption of hydrocarbons (HC) of various chemical nature (n-hexane, iso-octane, benzene,\\u000a toluene and p-xylene) on zeolite-clay material (ZCM) of Tatarsky-Shatrashansky deposit (Tatarstan, Russia). For comparison,\\u000a we also studied HC sorption on natural high-grade zeolite (Z) of St. Cloud Mine (New Mexico, USA), two local bentonite clays\\u000a and synthetic zeolite-molecular sieve Ms5A. As a result, sorption

Irina Breus; Alexandra Denisova; Sergey Nekljudov; Vladimir Breus

2008-01-01

440

Natural radioactivity levels in building materials used in Egypt  

NASA Astrophysics Data System (ADS)

All building materials contain various amounts of radioactive nuclides. The levels of natural radioactivity in 43 selected typical building materials used in the construction of walls, windows and doors were determined. For the first time, the radioactivity of iron was measured, revealing the existence of 60Co. A shielded high-purity germanium detector was used to measure the abundance of 226Ra, 232Th and 40K. The materials examined in this work showed radioactivity levels below the limit estimated from radium equivalent activity for acceptable radiation doses attributable to building materials, except for the fact that one gypsum sample showed higher levels of activity than average world levels. The studied building materials were classified according to the radium equivalent activities, which varied from highest to lowest levels as follows: clay, cement, brick, gypsum except from Abu-Zaabal, sand, wood, iron, glass and hydrated lime The existence of the 137Cs isotope in some building materials was confirmed and its concentration levels were determined (ranging from 0.04 to 21.156 Bq kg-1). The alpha-activity of radon was measured in a number of building materials using CR-39 detectors.

Ahmad, Fawzia

441

Nanocelluloses: a new family of nature-based materials.  

PubMed

Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants. PMID:21598362

Klemm, Dieter; Kramer, Friederike; Moritz, Sebastian; Lindström, Tom; Ankerfors, Mikael; Gray, Derek; Dorris, Annie

2011-05-20

442

NOVEL COMPOSITE MEMBRANES AND PROCESS FOR NATURAL GAS UPGRADING  

SciTech Connect

The first phase of this project involved the development of a high performance composite membranes for the treatment of natural gas. The objective of the second phase is to demonstrate the commercial potential of a full-size membrane module in a pilot scale field test. This phase is undertaken jointly with our commercial partner, UOP LLC. At the conclusion of Phase I, two composite membrane products had been developed for the enrichment (sweetening) of natural gas. The one was a low pressure membrane with a high CO{sub 2}/CH{sub 4} separation factor that falls within the target range of 25-30 (at 50 C) set for the program. This is a significant improvement over current commercial membranes that have separation factors of around 18-19. The second membrane had excellent high pressure capability and good contamination resistance, with a separation factor of 20-22. Based on the performance and the economic evaluation of the newly developed membranes, and with the input of UOP and DOE, it was decided to devote the demonstration phase of the program to the field testing and commercial evaluation of natural gas dehydration membranes. Due to the events of September 11, the program was also extended by 6 months until June 30, 2002. In Phase II, UOP has essentially completed preparation of the field test site. Site preparation included the re-design of the test system, purchase and installation of analytical equipment, and making the necessary piping and other hardware changes. IMS has produced two commercial sized dehydration membrane modules for the field tests. These have been successfully tested up to pressures expected in the field tests, and the modules have been shipped to the test site. The remainder of the program will comprise performance testing of the membrane modules, evaluation of the results and submission of the final report with recommendations.

Johann LeRoux

2002-02-01

443

Resistive Switching in Ag Nanowire/Polymer Composite Materials  

NASA Astrophysics Data System (ADS)

Bulk composites of electrically conductive nanoparticles within an insulating polymer matrix are insulating when the conductive particle concentration is below the electrical percolation threshold and conductive above it. However, we have observed reversible resistive switching with increasing voltage at room temperature in Ag nanowire/polystyrene composites with nanowire concentrations close to the percolation threshold. We have found the reversibility of the observed switching behavior to be temperature dependent which implies a diffusive process is involved. We propose the basis for resistive switching in these materials is the formation of field-induced filaments between adjacent nanowires that extend the percolated electrical network and increase the overall conductivity of the system. Here, we will compare our observations of resistive switching in Ag nanowire/polystyrene and Ag nanowire/poly(methylmethacrylate) bulk nanocomposites, explore the breadth of metal nanowire and polymer systems that exhibit resistive switching, and explore the underlying mechanism for filament formation.

Ford, Jamie; Mutiso, Rose; Winey, Karen

2012-02-01

444

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport  

NASA Astrophysics Data System (ADS)

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374° C and P<221bar) in a batch reactor. Process window and parameter influences were studied by a Design of Experiments (DOE) approach (1). A tar-like substance issued from thermal degradations is formed in greater or lesser quantities depending on the operating conditions, and coats the fibers. The appearance of the composite samples and the degree of conversion for the degradation at 250° C lead us to make a parallel with osmosis phenomena to explain the initiation mechanism of the degradation.

Oliveux, Géraldine; Le Gal La Salle, Eric; Bailleul, Jean-Luc

2011-01-01

445

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport  

SciTech Connect

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374 deg. C and P<221bar) in a batch reactor. Process window and parameter influences were studied by a Design of Experiments (DOE) approach (1). A tar-like substance issued from thermal degradations is formed in greater or lesser quantities depending on the operating conditions, and coats the fibers. The appearance of the composite samples and the degree of conversion for the degradation at 250 deg. C lead us to make a parallel with osmosis phenomena to explain the initiation mechanism of the degradation.

Oliveux, Geraldine; Le Gal La Salle, Eric [Laboratoire de Thermocinetique de Nantes (LTN), UMR CNRS 6607, Ecole Polytechnique de l'Universite de Nantes, Rue Christian Pauc, 44303 Nantes (France); Bailleul, Jean-Luc [Laboratoire Energetique, Mecanique et Materiaux(LE2M) de l'Institut Catholique des Arts et Metiers de Nantes, 35 avenue du champ de Manoeuvres, 44470 Carquefou (France)

2011-01-17

446

Fabrication, Processing and Characterization of Multidimensionally Braided Graphite/Epoxy Composite Materials.  

National Technical Information Service (NTIS)

This report describes research concerning the braiding, resin impregnation and characterization of multidimensionally braided fiber reinforced composite materials. These materials are an alternative to conventional laminated composite structures and have ...

A. B. Macander R. M. Crane E. T. Camponeschi

1984-01-01

447

Composition and structural aspects of naturally occurring ferrihydrite  

NASA Astrophysics Data System (ADS)

A series of naturally occurring ferrihydrites sampled from an acid mine drainage environment were characterized and compared with synthetic 2-line ferrihydrite using high energy X-ray total scattering and pair distribution function analysis, Scanning Transmission X-ray Microscopy (STXM), Transmission Electron Microscopy (TEM), BET N 2 surface area measurements, and chemical extractions in order to place constraints on their structural and physical properties as a function of composition. Overall, the short- and intermediate-range ordering of the natural samples is comparable to synthetic ferrihydrite. However, with increasing Al, Si, and organic matter contents, a decrease in particle size and an increase in structural disorder were observed. Silica is suspected to have a pronounced effect on the crystallinity of ferrihydrite as a result of its inhibitory effect on Fe polymerization and particle growth, and it is likely complexed at the surfaces of ferrihydrite nanoparticles. Aluminum, on the other hand may substitute for Fe 3+ in natural ferrihydrite. Organic matter is pervasive and intimately associated with ferrihydrite aggregates, and its presence during ferrihydrite precipitation may have contributed to additional structural disorder. The increase in impurity content affects not only the particle size and structural order of ferrihydrite but may also have a significant effect on its surface reactivity.

Cismasu, A. Cristina; Michel, F. Marc; Tcaciuc, A. Patricia; Tyliszczak, Tolek; Brown, Gordon E., Jr.

2011-02-01

448

Biomimetic fabrication of fibrin/apatite composite material.  

PubMed

Bidirectional diffusion of the Ca and PO4 solutions into the fibrin gel was performed at various pH conditions and fluoride concentrations to generate organic/inorganic composite materials mimicking biomineralization. The minerals produced in this system had a higher crystallinity than those generated by the solution mineralization system. The minerals generated in fibrin gel varied depending on the pH conditions as follows: Dicalcium phosphate dihydrate (DCPD) in the noncontrolled pH solution, the DCPD and octacalcium phosphate (OCP) mixture at pH 7.4, and the OCP and hydroxyapatite (HAp) mixture at pH 9.0. When fluoride ions were added in the range of 2-500 ppm, the minerals produced at pH 7.4 altered from OCP/HAp to HAp/fluorapatite (FAp). In addition, the crystallinity of the obtained minerals increased with an increase in fluoride ion concentration, and the solubility was inversely correlated to crystallinity. In conclusion, we established a novel fabrication method for synthesizing organic/inorganic composite materials composed of fibrin and calcium phosphate and revealed that the characteristics of the minerals in the synthesized material can be controlled by the fabrication condition. PMID:18085654

Yoh, Rui; Matsumoto, Takuya; Sasaki, Jun-Ichi; Sohmura, Taiji

2008-10-01

449

Present and Future Automotive Composite Materials Research Efforts at DOE  

SciTech Connect

Automobiles of the future will be forced to travel fi.uther on a tank of fuel while discharging lower levels of pollutants. Currently, the United States uses in excess of 16.4 million barrels of petroleum per day. Sixty-six percent of that petroleum is used in the transportation of people and goods. Automobiles currently account for just under two-thirds of the nation's gasoline consumptio~ and about one-third of the total United States energy usage. [1] By improving transportation related fiel efficiency, the United States can lessen the impact that emissions have on our environment and provide a cleaner environment for fiture generations. In 1992, The Department of Energy's (DOE) Office of Transportation Materials completed a comprehensive program plan entitled, The Lightweight MateriaIs (LWko Multi-Year Program Plan, for the development of technologies aimed at reducing vehicle mass [2]. This plan was followed in 1997 by the more comprehensive Office of Advanced Automotive Technologies research and development plan titled, Energy Eficient Vehicles for a Cleaner Environment [3] which outlines the department's plans for developing more efficient vehicles during the next ~een years. Both plans identi~ potential applications, technology needs, and R&D priorities. The goal of the Lightweight Materials Program is to develop materials and primary processing methods for the fabrication of lighter weight components which can be incorporated into automotive systems. These technologies are intended to reduce vehicle weight, increase fuel efficiency and decrease emissions. The Lightweight Materials program is jointly managed by the Department of Energy(DOE) and the United States Automotive Materials Partnership (USAMP). Composite materiak program work is coordinated by cooperative research efforts between the DOE and the Automotive Composites Consortium (ACC).

Warren, C.D.

1999-07-03

450

VISCOELASTIC PROPERTIES OF NATURAL RUBBER COMPOSITES REINFORCED BY DEFATTED SOY FLOUR AND CARBON BLACK CO-FILLER  

Technology Transfer Automated Retrieval System (TEKTRAN)

Filler mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce natural rubber (NR) composites and their viscoelastic properties were investigated. DSF is an abundant and renewable commodity and has a lower material cost than CB. Aqueous dispersions of DSF and CB were firs...

451

Organic materials in planetary and protoplanetary systems: nature or nurture?  

NASA Astrophysics Data System (ADS)

Aims: The objective of this work is to summarize the discussion of a workshop aimed at investigating the properties, origins, and evolution of the materials that are responsible for the red coloration of the small objects in the outer parts of the solar system. Because of limitations or inconsistencies in the observations and, until recently, the limited availability of laboratory data, there are still many questions on the subject. Our goal is to approach two of the main questions in a systematic way: - Is coloring an original signature of materials that are presolar in origin ("nature") or stems from post-formational chemical alteration, or weathering ("nurture")? - What is the chemical signature of the material that causes spectra to be sloped towards the red in the visible? We examine evidence available both from the laboratory and from observations sampling different parts of the solar system and circumstellar regions (disks). Methods: We present a compilation of brief summaries gathered during the workshop and describe the evidence towards a primordial vs. evolutionary origin for the material that reddens the small objects in the outer parts of our, as well as in other, planetary systems. We proceed by first summarizing laboratory results followed by observational data collected at various distances from the Sun. Results: While laboratory experiments show clear evidence of irradiation effects, particularly from ion bombardment, the first obstacle often resides in the ability to unequivocally identify the organic material in the observations. The lack of extended spectral data of good quality and resolution is at the base of this problem. Furthermore, that both mechanisms, weathering and presolar, act on the icy materials in a spectroscopically indistinguishable way makes our goal of defining the impact of each mechanism challenging. Conclusions: Through a review of some of the workshop presentations and discussions, encompassing laboratory experiments as well as observational data, we infer that both "nature" and "nurture" are instrumental in the coloration of small objects in the outer parts

Dalle Ore, C. M.; Fulchignoni, M.; Cruikshank, D. P.; Barucci, M. A.; Brunetto, R.; Campins, H.; de Bergh, C.; Debes, J. H.; Dotto, E.; Emery, J. P.; Grundy, W. M.; Jones, A. P.; Mennella, V.; Orthous-Daunay, F. R.; Owen, T.; Pascucci, I.; Pendleton, Y. J.; Pinilla-Alonso, N.; Quirico, E.; Strazzulla, G.

2011-09-01

452

Parameterization of structures in HE composites using surrogate materials: A small angle neutron scattering investigation  

SciTech Connect

High explosive materials used in the nuclear stockpile are composites of crystalline high explosives (HE) with binder materials, such as Estane. In such materials, there are naturally occurring density fluctuations (defects) due to cracks, internal (in the HE) and external (in the binder) voids and other artifacts of preparation. Changes in such defects due to material aging can affect the response of explosives due to shock, impact and thermal loading. Modeling efforts are attempting to provide quantitative descriptions of explosive response from the lowest ignition thresholds to the development of full blown detonations and explosions, however, adequate descriptions of these processes require accurate measurements of a number of structural parameters of the HE composite. Since different defects are believed to affect explosive sensitivity in different ways it is necessary to quantitatively differentiate between defect types. The authors report here preliminary results of SANS measurements on surrogates for HE materials. The objective of these measurements was to develop methodologies using SANS techniques to parameterize internal void size distributions in a surrogate material, sugar, to simulate an HE used in the stockpile, HMX. Sugar is a natural choice as a surrogate material, as it has the same crystal structure, has similar intragranular voids and has similar mechanical properties as HMX. It is used extensively as a mock material for explosives. Samples were used with two void size distributions: one with a sufficiently small mean particle size that only small occluded voids are present in significant concentrations, and one where the void sizes could be larger. By using methods in small-angle neutron scattering, they were able to isolate the scattering arising from particle-liquid interfaces and internal voids.

Mang, J.T.; Hjelm, R.P.; Skidmore, C.B.; Howe, P.M.

1996-07-01

453

Development of composite materials for PEFC bipolar plates  

SciTech Connect

Polymer electrolyte fuel cells (PEFCs) are attractive alternatives to traditional energy sources for both stationary and transportation applications, provided they can be manufactured at a reasonable cost. The most costly and problematic components of fuel cell stacks may be bipolar plates. Besides meeting cost constraints, bipolar plates must possess a host of other properties including low gas permeability, corrosion resistance, low weight, high strength, and manufacturability. While the authors have developed a baseline composite material that meets these requirements, further optimization and development have resulted in significant improvements in properties and processability.

Busick, D.; Wilson, M.

2000-07-01

454

Collagen hydrolysate based collagen/hydroxyapatite composite materials  

NASA Astrophysics Data System (ADS)

The aim of this study was to study the influence of collagen hydrolysate (HAS) on the formation of ternary collagen-hydrolysate/hydroxyapatite composite materials (COLL-HAS/HA). During the precipitation process of HA, a large amount of brushite is resulted at pH = 7 but, practically pure HA is obtained at pH ? 8. The FTIR data reveal the duplication of the most important collagen absorption bands due to the presence of the collagen hydrolysate. The presence of collagen hydrolysate is beneficial for the management of bone and joint disorders such as osteoarthritis and osteoporosis.

Ficai, Anton; Albu, Madalina Georgiana; Birsan, Mihaela; Sonmez, Maria; Ficai, Denisa; Trandafir, Viorica; Andronescu, Ecaterina

2013-04-01

455

Characterization and the Pattern of Surfaces of Sealant with nano size Composite Materials  

NASA Astrophysics Data System (ADS)

Nano composite sealant is low viscosity, room temperature cured, opaque and flowable nature. They have variety of uses such as potting, pressure sealant and shock resistant. Most important factor influencing use of fillers in polymer composites is their ability to effectively transfer the applied load in the matrix. The effective utilization of fillers in composites for structural applications depends strongly on the ability to disperse the nano fillers homogeneously in the matrix without damaging them. R-Belite supper epoxy adhesive (RBSEA) were formulated with different nano fillers (KCl, Al2O3, ZrO2, SiO2, ZrO2) at room temperature. The composite were prepared with the 0.02 to 0.10 weight ratios to promote the nucleation of the nanoparticles in the applied sealant. Two main problems which arise in improving the properties are poor dispersion of the fillers in the composite and weak bonding between nano fillers and the matrix. These problems are solved by mechanical and chemical means. It was observed that mechanical properties like tensile strength, elongation hardness etc and thermal properties were also improved with incorporation of nanofillers in the working applied polymer matrix. The dispersion of nano fillers in polymer matrix is studied by Scanning electron microscopy (SEM). The results confirm the presence of nanomaterial in RBSEA/fillers nanocomposites. SEM is also used to characterize the pattern of surfaces with nano size composite materials.

Quddos, A.; Samtio, N. H.; Syed, A. M.

2013-06-01

456

Task 5.9 use of coal ash in recycled plastics and composite materials. Topical report  

SciTech Connect

The goal of this research project by the Energy & Environmental Research Center (EERC) was to determine the potential for coal ash to serve as a {open_quotes}functional filler{close_quotes} in plastics and other composite materials, with special emphasis on recycled plastics. The term functional filler is intended to indicate that the material added to the plastic does more than take up space and extend the use of the polymer. Determining the functional filler potential of ash was not the only intent of this project, since another prime objective was to find a use for materials currently considered waste. The term functional filler also opened a door to the use of cenospheres, which are currently marketed and for which there is sufficient market demand that they do not fit the category of a waste even though they are a product of coal combustion. Cenospheres, hollow spherical ash particles, were selected because of their unique properties. Although they currently have commercial applications, the unique nature of these materials make them an excellent candidate for use as a functional filler in composites. The ability to produce a commercially viable product from waste streams and a recycled material is a positive step toward reducing solid waste. The first task, since there are numerous types of coal ash, was to select suitable ash types for use in this project. Three basic types of material were selected: fly ash, a bottom ash, and a unique form of coal ash known as cenospheres.

Hassett, D.J.; Dockter, B.A.; Eylands, K.E.; Pflughoeft-Hassett, D.F.

1995-11-01

457

Task 5.9 - use of coal ash in recycled plastics and composite materials  

SciTech Connect

The goal of this research project by the Energy & Environmental Research Center (EERC) was to determine the potential for coal ash to serve as a {open_quote}functional filler{close_quotes} in plastics and other composite materials, with special emphasis on recycled plastics. The term functional filler is intended to indicate that the material added to the plastic does more than take up space and extend the use of the polymer. Determining the functional filler potential of ash was not the only intent of this project, since another prime objective was to find a use for materials currently considered waste. The term functional filler also opened a door to the use of cenospheres, which are currently marketed and for which there is sufficient market demand that they do not fit the category of a waste even though they are a product of coal combustion. Cenospheres, hollow spherical ash particles, were selected because of their unique properties. Although they currently have commercial applications, the unique nature of these materials make them an excellent candidate for use as a functional filler in composites. The ability to produce a commercially viable product from waste streams and a recycled material is a positive step toward reducing solid waste. The first task, since there are numerous types of coal ash, was to select suitable ash types for use in this project. Three basic types of material were selected: fly ash, a bottom ash, and a unique form of coal ash known as cenospheres.

Hassett, D.J.; Dockter, B.A.; Eylands, K.E.; Pflughoeft-Hassett, D.F.

1995-07-01

458

Task 6.7.3 - Interfacial Mass Transport Effects in Composite Materials  

SciTech Connect

Advanced metal-matrix composites (MMCS) consisting of titanium-based alloys possess some unique mechanical, physical, and chemical characteristics that make them highly desirable for aircraft and gas turbine engines. Tailoring MMC properties is essential for advanced product design in materials processing. The main factors that affect materials processing and, further, the nature of a metal-ceramic interface, its structure, and morphological stability is liquid surface mass transport related to adhesional wetting (physical effect) and reactive wetting (chemical effect).' Surfaces and interfaces dominate many of the technologically important processes in composite materials such as liquid-solid sintering and joining. The objective of this work is threefold: 1) to get insight into the role of the nonstoichiometry of chemical composition in ceramic materials used as reinforcement components in MMC processing, 2) to extend previous energetic analysis of mass transport phenomena to wetting behavior between liquid metal and the quasi-solidlike skin resulting from the presolidification of liquid on nonstoichiometric solids on a scale of interatomic distance, and 3) to provide experimental verification of our concept.

Jan W. Nowok

1998-02-01

459

Task 6.7.3 - Interfacial Mass Transport Effects in Composite Materials  

SciTech Connect

Advanced metal-matrix composites (MMCS) consisting of titanium-based alloys possess some unique mechanical, physical, and chemical characteristics that make them highly desirable for aircraft and gas turbine engines. Tailoring MMC properties is essential for advanced product design in materials processing. The main factors that affect materials processing and, further, the nature of a metal-ceramic interface, its structure, and morphological stability is liquid surface mass transport related to adhesional wetting physical effect) and reactive wetting (chemical effect). Surfaces and interfaces dominate many of the technologically important processes in composite materials such as liquid-solid sintering and joining. The objective of this work is threefold: 1) to get insight into the role of the nonstoichiometry of chemical composition in ceramic materials used as reinforcement components in MMC processing, 2) to extend previous energetic analysis of mass transport phenomena to wetting behavior between liquid metal and the quasi-solid like skin resulting from the presolidification of liquid on nonstoichiometric solids on a scale of interatomic distance, and 3) to provide experimental verification of our concept.

Jan W. Nowok

1998-02-01

460

Micromechanical approach to damage mechanics of composite materials with fabric tensors  

Microsoft Academic Search

The purpose of this study is to apply continuum damage mechanics – introduced through the concept of fabric tensors – to composite materials within the framework of the theory of elasticity. A directional data model of damage mechanics for composite materials will be developed using fabric tensors. The introduction of fabric tensors into the analysis of damage of composite materials

G. Z. Voyiadjis; Z. N. Taqieddin; P. I. Kattan

2007-01-01